landscaping-plants.pdf

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INTRODUCTION

(Figures to be appended later)

Purpose

This book intends to familiarize inclined persons, whether professional botanist or not, to

the commonest of the Indian trees. The book covers whole of India excluding the Himalayas, a

region substantially differing from the remaining country due to a flora that is biogeographically

different, diverse, well described and illustrated. This book provides a field identification key

and descriptions of habit, leaf and bark characters, habitat preference, geographical distribution,

seasonality and other important aspects including technical ones like the nomenclature.

The book is a contribution to the series Lifescape published by the Indian Academy of

Sciences. The objectives of the book, as of the series, include familiarizing the reader, primarily

amateurs with common, important and interesting Indian biota. The book may be useful even for

technical experts or specialists, as a comprehensive reference. The book may also serve as a

resource material for teaching college botany and will inspire more amateur naturalists than

today.

Excellent job has been done in these directions by the phenomenal `Book of Indian Birds’

scripted by the doyen of Indian natural history Dr. Saalim Ali. The book has triggered scores of people from all walks of life to pursue bird watching. This inspired springing of several bird

watching clubs, including in schools and colleges allover the country. Of late, this informal

movement has consolidated itself to conduct a formal annual bird count every year on Dr. Salim

Ali’s birth anniver sary. The data compiled together is a crucial contribution to monitoring the

quality of our living environment. Trees are common and important, useful organisms, if not as

charming or appealing as birds; around us everywhere, from mountain forests to sea coasts and

from villages to mega-cities. Thus, the lack of a simple, attractive and useful fieldguide is

unfortunate, painful and hard to explain.

Earlier work


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Number of noteworthy attempts to bring out a fieldguide for trees fall short of Dr. Saalim

Ali’s job on several counts. This book has causally tried to avoid several drawbacks from which

the earlier attempts suffer, as described below. However, there is no claim that the present book

is any match for Dr. Saalim Ali’s work, although that remains the intention. The best

known of the books of Indian trees is the one by Charles McCann, a British botanist earlier in the

century. It remains till date a very well illustrated and elaborately written book with very

interesting anecdotes and writing style. It covers about 100 species, many of them exotic i.e.

introduced from abroad but widely cultivated in India. A similar book by Blatter and Millard

covers nearly half the species, again mostly exotic. Amongst Indian authors, the book on

common trees by Santapau is comprehensive with good line drawings. It covers barely 60

species, unfortunately most them are exotic. A very similar book is that on beautiful flowering

trees by Randhawa, with some more species, including indigenous ones. The first effort of giving

due representation to many indigenous species amongst 100 species covered was done of late by

Bole and Vaghani in their fieldguide to common Indian trees. The field identification key is an

innovative approach though replete with technical terms and presented unattractively. The book

suffers from very poor illustrations and makes an information packed yet drab reading.

The latest book on Indian trees by Sahani is excellent and may stand up to Dr. Ali’s

work, but for its coverage limited to just 100 species. It gives much better representation to

indigenous species, for instance Himalayan and Western Ghats, than other books. The number of

species covered in most of these books is around 100, which appears too small to adequately

represent the diversity of Indian trees. The strength of Sahani's book lies in its superb line

drawings and elaborate yet attractive information, only next to that by McCann. The least

known and perhaps the best of all the books is the one by NCERT which covers some 225

species, with adequate representation to most important wild species from every region of India.

Line drawings have are neat and attractive. Despite being catchy, focussed and having most

smooth flow, the description is meager. Lastly one must appreciate the well-illustrated volumes

of fieldguide on Himalayan flowering plants by Poulnin and Stainton. The description is brief

yet informative and covers all important species especially from Western Himalayas. This makes

it unnecessary to repeat the same here. The photographs are unmatched.


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Scope

The Indian tree flora comprises of nearly 2000 species belonging to about 800 genera and

150 families of flowering plants. This vast diversity ranks 10th in the world and even higher

relative to the area. Of these, peninsular (see Fig. 1) i.e. in a broad sense the extra Himalayan,

India hosts some 800 species from 250 genera and 125 families. This includes majority of the

cultivated and exotic species. Nearly 40% of the Indian trees species are Indo-Malayan i.e.

widely distributed in south-east Asia besides India. The proportion of Indo-Malayan elements is

higher in the deciduous forests (see Fig. 2) that shed most of leaves during spring. The species

shared with Africa or widely distributed in the tropics are less than half of this, their proportion

being higher in the drier, thorny, desertic vegetation as in the western India. The evergreen

forests from the Western Ghats and north-eastern India have predominance of endemic species

i.e. those restricted to India as a whole or only to those regions. These endemic elements

comprise up to 60% of all species in the broad leaved evergreen forests, confined to these

regions. The temperate, needle leaved forests of upper Himalaya have species widely distributed

in highlands till Europe in the west and Japan in the east. Amongst introduced tree species, south

American contingent is most significant. Such contribution of various biogeographic elements

due to land connectivity and climatic variety, besides human aided introductions has made Indian

tree flora so diverse.

The book describes and illustrates 165 species belonging to about 140 genera and 50

families. Besides, about 200 species resembling the described ones are mentioned in the passing,

emphasising their distinctive characters but not description. Available information on tree

enumeration by the forest department and ecologists suggests that the species covered by the

book, which are amongst the commonest, might cover over 95% of the standing trees in the

region. It covers most species comprising the less diverse deciduous forest and fewer in the

evergreen forests, which are hyper-diverse. Of the species covered 15% are distributed in a wide

variety of vegetation types (i.e. are `wide niched’ or `generalists’) while 20% are restricted to

single vegetation type (i.e. are `narrow niched’ or `habitat specialists’).

About 90% of the species described are found in the forests and scrub i.e. natural

vegetation. However, only half of them are exclusive, the remaining are also inhabit or are


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cultivated in the plantations and generally around human habitations. Of the total species, some

80% are found in forests, little less than half of them exclusively so. Nearly 60% of the species

inhabit degraded vegetation such as savanna and scrub, only 15% being exclusive. Amongst

forests, nearly three fourth of the species are found in moist forests, whether deciduous or

otherwise, but less than half of them are exclusive. Nearly two third of the species are found in

evergreen/ semi-evergreen forest, nearly a third being exclusive. The manmade habitat types viz.

plantations and habitation surroundings host little less than half the total species but just one

fourth of such human related i.e. about 10% of the total species, are exclusive to human

company. The most speciose i.e. species rich habitat type is semi-evergreen forest while type

with highest proportion of restricted i.e. specialist species is the evergreen forest. Scrub mostly

hosts the widespread species. This overall pattern of species representation in the book broadly

mimics the pattern of distribution of overall tree flora.

The intended nature of contents of various sections used in species description in the

book is as below.

Field identification characters

A tree, by forester’s and ecologist's definition, is a woody plant that attains diameter of

10cm (30cm girth) or more at the breast height (130cm above ground). A limit of 4cm diameter

(10cm girth) is used occasionally such as in the tree felling regulations of the municipal

corporations in India. The trees differ from other plants in having cambium tissue that accounts

for the woody nature of the stem. Trees differ from shrubs (see Fig. 3) which are also woody.

Shrubs branch extensively from the base near the ground while the trees branch much above and

usually have a single stem emerging from the ground level.

Traditionally, trees were identified and described with emphasis on reproductive

characters like flowers and fruits. This method works well with herbs, which are annual, thus

lacking distinguishing characters like the bark and easily enabling collection and preservation of

the whole plant. Use of reproductive characters may be necessary for proper botanical

classification of trees. However, use of reproductive characters for day to day identification by

field biologists or amature naturalists is difficult and unnecessary. For, the flowers and fruits of


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trees may not be available during most of the year when the trees can be visited unlike herbs that

are visited generally during limited flowering/ fruiting period i.e. monsoon. Secondly, flowers

and fruits of trees may often be borne at heights beyond our normal reach, atop the 15-20 m tall

tree, making their collection difficult. Moreover, few tree species having large, woody or fleshy

fruits and/ or flowers, make preservation of specimens very difficult.

The characters that one can relatively easily study in case of trees due to year round

availability and being within normal reach and easy to preserve are those of leaf. The bark

characters are also easy to study in the field but not necessarily easy to preserve. The first famous

attempt to use these vegetative characters alone thus avoiding the reproductive ones was by

Whitemore in his field key to Malayan tree flora, which covered over 1000 species. In India, the

credit for popularising such studies goes to Pascal and Ramesh who prepared a well-illustrated

vegetative identification key for some 500 tree species of the Western Ghats. Actually, the first

such key was pioneered by Balsubramaniam et al for 300 species of trees in southern Western

Ghats. A similar approach is adopted here, as its success has already been demonstrated in the

Western Ghats or even richer Malayan tree flora.

How to watch a tree?

Binoculars, so unmistakably used by bird watchers, are useful if not indispensable even

for tree lovers, especially in the evergreen forests with tall trees, many of them bearing small

leaves. Besides, keen observation is needed to locate some basal branches or shoots (see fig. 4)

for closely and reliably observing or collecting leaves, if most branches and leaves are situated

high. If the leaves of a particular tree are unavailable, it is wise to locate another tree with very

similar stem characters and observe if that tree has any basal branches or shoots. If the fresh

leaves are any way not available, one must bow low to observe the ground litter (see fig. 5). It is

a delight to identify trees overheads just by looking beneath, at the fallen leaves, flowers or

fruits, along a forest walk. In a dense forest, leaves of many species are mixed in the litter. Thus,

one must ascertain the most abundant leaves at a spot and assume them to be fallen from the

branches overhead, belonging to the nearest tree. However, it is necessary to ensure that the tree

overhead is in its leaf shedding phase, as evident from few yellowish or reddish leaves and

unusually empty branchlets. Otherwise, it is likely that the nearest tree has shed most of its


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leaves long ago, dumped at the bottom of the litter, covered by the recently fallen leaves of other

neighbouring trees. Upon obtaining the leaves, it is very useful to crush and smell them, hold

against sunlight to observe extra-marginal transparent ring or glands along the petiole, margin

teeth or on the surface (see Fig. 6). It is equally useful a habit to carry a small knife for making a

small cut on the bark and observe the blaze, sap secretion or smell, if any. A field identification

key based on these characters is provided in Annexure 1). Besides, lists of species with peculiar

appearance when in new leaves or fully flowered stage are provided in Annexure 2.

Taxonomic classification

The basic unit of biological classification is a species. Though several definitions of

species exist, the simplest and the most widely known one states that a species comprises of the

set of individuals that can interbreed and produce fertile offsprings with the same characters as

parents. Thus, though lion and tiger can interbreed to produce tilons or ligers, those are not

fertile. Hence, a lion and a tiger do not belong to the same species.

Several species with some common basic features constitute a genus. For instance,

several species that resemble in having round, fleshy, edible fruits; have evergreen, oval-elliptic

leaves with obscure secondary nerves and sour taste; have bark with reddish blaze exuding

yellowish sap when cut; belong to genus Garcinia. Similarly, many thorny species with doubly

compound leaves and round flowers with numerous stamens rough bark belong to genus Acacia.

The species within a genus often look alike in terms of vegetative characters and sometimes

differ only in the reproductive characters like in case of the genus Acacia.

Several genera similar to each other and distinct from others make up a family. For

instance, the mango, cashewnut, marking nut, and related trees from other genera make up the

family Anacardiaceae. Some vegetative characters also are common to the whole family. For

instance, all the Myrtaceae i.e. Eucalypt family members have leaves with transparent

gland-dotted surface; all Rutaceae i.e. lemon family members have fragrant leaves with

transparent gland dotted surface. In simpler terms, species are like offsprings in the smallest

human family belonging to one genus. The genus is like the parents in a family and different

genera like offsprings from that generation. Several such parental siblings make up the whole


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family identified by the surname (see Fig. 7). In usual description, it suffices to mention the

identity of species and the genus but not the family, which becomes obvious to the botanist once

the genus is known.

Scientific Nomenclature

Linneaus, the great 18th century biologist from Britain first introduced the system of

binomial nomenclature i.e. two names, one referring to genus and another to species. The system

probably had its origins in a system then prevalent in Kerala, taught by an Ezhawa medicineman

to Van Rheede, a 17th

century Dutch botanist, who used it for describing Malabar plants.

Linneaus later referred this work developed the binomial nomenclature system further, soon

becoming popular globally. Europeans had just spread world wide then and were actively

exploring new regions and their biota, much of it being new to science. These new species were

constantly getting named and described, and their specimens were being sent to Europe for the

reference of other taxonomists. However, communication was very slow then and taxonomic

publications also very few. A ship from India would take months to reach England and land

journey was neither fast nor easier. Thus, often a species occurring in two different countries or

even continents was separately encountered and described by different names by taxonomists

from those regions with little direct contact, unlike phone, fax, email and airmail available today.

Researchers in Europe had quicker access to museum specimens as well as literature.

They soon realized that the same species was being described by different scientists by different

names. To retain only a single binomial name for one species, rules were evolved. Basically, the

name used first i.e. dated earliest was retained as valid name and the rest were relegated to

synonyms. Besides the date of publication, other criteria were also invoked giving rise to an

elaborate international code of botanical nomenclature. Thus, although the original purpose of

Linnean system of binomial nomenclature was to assign a single name to a species, we have

today most species identified with a set of names one of them valid and the rest synonyms. But

this began not because the system was faulty but due to the communication difficulties.

Further, research on classification and nomenclature constantly reveals older and older

literature sources to researchers. Thus, even the valid names keep changing over time, for some,


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if not many species. This book employs most frequently used valid names in recent Indian

publications. Citing the most commonly referred synonyms here may make it is easy to search

the species mentioned here in other literature sources. There is no claim however that the names

cited here as the valid names are in fact valid as per the international code. Intention of the book

is to marry popular information with scientific and not to stretch to any extreme.

Etymology of the scientific nomenclature has been adopted from the excellent book by

Nayar titled `Meaning of the Indian flowering plant names’ that primarily covers generic names.

Also referred is a simple yet useful book by Dixit, covering generic as well as specific names,

primarily from western India.

Folk nomenclature and folklore

The common English names are available only for a few species, from books cited

earlier. Vernacular names have been largely sourced from a book by the name `useful plants of

India’ published by the Council of Scientific and Industrial Research, Government of India. It is

unfortunate that etymology of vernacular names which could be very interesting and useful,

flowing from constant interaction of people with live trees rather than limited encounter of the

scientists, primarily with the dead specimens. Interestingly, vernacular names have often

influenced or crept into the Latin nomenclature e.g. Saraca asoca derived from the vernacular

name Ashoka.

It is unfortunate that there are no standard books on folklore associated even with the

most important species. Further, this aspect is neglected in most books to date. The efforts in this

book are thus very preliminary, the only intention being to encourage more people to look at

these vital aspects, with considerable indicative value about properties of species. Some literature

could be found in regional languages, in mythological stories, folk songs etc. which needs

careful collection and study.


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History

Several tree species have been introduced in India since centuries and tens of them have

become integral part of Indian landscape and culture such as sandalwood and coconut. Literature

about history of these introductions and further spread in India (see Fig. 8) is available. However,

consensus may be elusive in some cases like sandalwood about area of origin and date and route

of introduction. It is however a very interesting and illuminating study subject having a bearing

on our future relationship with trees. Some introduced species like coconut do not regenerate on

their own and have to be planted through special efforts. Some others like sandalwood spread on

their own through natural regeneration. However, many exotic species are unable to compete

with local species and get eventually edged out by saplings natural trees in the absence of human

intervention such as cutting, grazing, fire etc. Such escape and spread could be attributed to lack

of predator species from the area of origin. But in case the predator reaches this land as happened

in the case of Leucena in early '90s or some other predator gets established, the species

population may suddenly dwindle.

Treatise on forest ecology by Puri et al . and pioneering research by Chandran provide

some interesting insights can be gained in the vegetation history. At least two time-scales can be

visualised, one being geological, ranging over millennia while other being ecological, ranging

over decades or centuries. The Indian vegetation is partly the result of confluence of several

biogeographic elements following the union of Indian mainland with Asian plate during the

geological past. This is particularly true of Himalayas that rose as a result of this collision.

Himalayas are colonised mainly by the temperate and Artict flora ranging from Europe in the

West to Japan in the East. On the contrary, peninsular India, especially Western Ghats and its

evergreen forests are dominated by the endemic elements, not found in other parts of the world.

Most of these endemic species are very old i.e. palaeoendemics while Himalaya mountain

ranges which were borne much later than the Western Ghats harbour some neoendemic species.

Some of the Western Ghats species are very old, such as Atuna indica from family

Chrysobalanaceae, which is extensively diversified in the neotropics and hardly represented in

the palaeotropics. It is likely that some such species in the Western Ghats bear testimony to the

days when continents like America, Africa and Asia constituted a single landmass called


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Gondwana. This may also explain some of the similarities in peninsular flora with the African

flora, while much is explained by the continuity of landmass between northwestern India and

western Asia bordering African continent. The latter accounts for similarity in the desertic flora

of the two continents, dominated by the Ethiopian elements. However, much of the peninsular

flora inhabiting intermediate moisture zones between the desertic northwest and the humid

Western Ghats are dominated by Indo-Malayan elements, which largely constitute the deciduous

forests, both dry and moist.

Amongst the most talked about factor affecting forest composition over ecological scale

is tree felling. Besides reduced density of the target species, felling may create canopy gaps,

inviting pioneer, sun-loving species to colonise, especially in the shady, evergreen forests. Forest

fires favour dominance of fire resistant species having thick bark and good coppicing ability like

Careya arborea while destroying the delicate species. Thus, fires may gradually convert an

evergreen forest into semi-evergreen at the outset and later, deciduous forest full of fire tolerant

species. Fires are limited though in the evergreen forests due to prevailing moisture and shade,

including the moist litter on the floor. Deciduous forests and savannas are more fire-prone and

thus interspersed with grassy undergrowth especially in savannas. Local people deliberately put

many of these fires during summer in the belief that the fires would be followed by quick growth

of grass shoots relished by the cattle. The grass seeds survive and even benefit from fires.

Amongst trees, only a few species with hard seed coat survive and benefit. Besides fires, cattle

may also directly destroy the vegetation, particularly saplings. The evergreen trees mostly have

thick leaves that are not relished by the cattle, in contrast to thin leaves of many deciduous

species. Cattle grazing also indirectly affects vegetation due to lopping by the cattle owners for

fodder. Frequent grazing and lopping such as for farm manure favours growth of thorny species

and scrubby vegetation, with many coppice shoots. Such heavily lopped vegetation may also

provide ideal site for infestation by parasitic plants like Viscum and Loranthus. Human harvests

of the other kind such as seeds may cause long term changes, primarily in species composition.

Favourable human influences on vegetation include direct ones like the sacred groves or

protected areas and indirect protection such as through reservoirs. Sacred groves are the oldest

known tradition of nature conservation, since the days of slash and burn agriculture. It still


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persists strongly in areas of shifting cultivation, while diluted or converted forms like temple

groves in settled agricultural or even semi-urban areas. Religious beliefs and taboos that threaten

deity's wrath following tree cutting in the grove protect these. These must have once dotted much

of the Indian landscape especially in tribal zones like the Western Ghats or North eastern India.

However, their number rapidly declining for the last few decades given the impact of overall

socio-economic development and concomitant fading of religious faith. Sometimes, felling the

majestic trees from the grove yields handsome returns. Many groves shelter relics of past,

pre-human intervention vegetation, often different from surrounding vegetation. For instance, the

groves may harbour many evergreen species in high rainfall zone though the surrounding forests

might be replete with deciduous species favoured by canopy gaps due to tree felling, besides

fires and grazing, usually not influencing the grove.

Recent times saw traditions of nature conservation taking the form of royal hunting

preserves in the Mahabharata and Mughal era while that of `game reserves' during the British

era. This gave way to numerous wildlife sanctuaries and national parks in the independent India

which now cover over 4% of the country's landmass. Number of reservoirs came up in this

period, submerging invaluable forests. However, the reservoirs also cut off the access of felling

officials and smugglers, local people to the forests, resulting in protection of forests remaining in

the catchment, Periyar tiger reserve being a classic example. Some of the promotional measures

may include encouraging artificial regeneration such as extensive tree plantations or aerial

seeding etc., primarily focussing on exotic commercial species, not natural vegetation. Some

measures may include coppice growth of natural yet economically valuable species like the Sal

tree.

Interplay between such protection measures and the degrading forces on the other create

a mosaic of vegetation types in a landscape, in a dynamic equilibrium or even change, known as

succession. The degradation may change an evergreen forest into semi-evergreen and later, moist

deciduous forests, to be followed by woodlands or `open forests' in forestry terminology. Further

felling, lopping, grazing may lead to dwarfing of the trees and growth of shrubby ground cover,

giving the vegetation an appearance of scrub i.e. admixture of trees and shrubs to begin with and

later thickets i.e. clumps of only shrubby growth. On the other other hand, frequent fires may


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consume shrubby growth and favour grass growth, amidst scattered trees, giving rise to savanna

physiognomy. Further fires may even make the trees shrubby, changing vegetation type into

`shrub savanna' before degrading into grassland. Such vegetation degradation processes is

termed as retrogression while upgradation is termed progression. Progression is the reverse of

degradation, for instance, upgradation of scrub or savanna into forest. The progression may not

proceed beyond the maximum vegetation allowed by the climate and soil, termed as potential

vegetation of a place. Thus, evergreen forests may never grow in drier tracts fit for only

deciduous forests.

These successional processes provide opportunities to species having different

environmental choices to co-exist and even flourish. Successional processes that are natural and

operate at smallest scale may include canopy gaps creation due to treefall, especially in clumps

due to lightening and thundershowers. In the dense canopied evergreen forests such treefalls

provides some sunloving species, unable to germinate or survive under the shade, an unusual

opportunity to colonise and grow. Such species are termed as pioneers species. Some of them

even colonise recent land falls in hilly terrain and other eroded sites. Later, when the pioneer

species grow and produce enough shade and loosen the soil, conserve some soil moisture; late

successional species may start regenerating and growing. Climax species are the last of the late

successional species in chronological sequence and prosper under dense shade and high

humidity. The ecological role played by a species may be defined as its niche, as defined later.

Leaf Shedding

Some trees shed most of their leaves during spring i.e. after winter, in January and

February. Some shed it even or during summer i.e. March to May. Such species that shed their

leaves in bulk are termed as deciduous (see Fig. 9). These are sensitive to soil moisture regimes.

Leaf shedding in bulk minimizes water loss due to evaporation from the leaves. This particularly

helps during dry season, when moisture deficiency is high. Besides, the leafless period followed

by flowering period as the trees can spend most of their nutrition and other investment on their

reproductive organs rather than vegetative organs like leaves. Other species that generally grew

in moist areas with low soil moisture stress are more resistant to minor changes in soil moisture

regimes. These species therefore continually shed and regain leaves, but never in bulk. These


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species are termed as evergreen. Some evergreen species may even inhabit drier tracts such as

Manilkara hexandra (wild Sapota) dominating the lowlands adjoining the eastern coast.

Typically, evergreen species have dark coloured, thick, smooth and even waxy leaves, so as to

minimize the water loss through evapotranspiration.

Canopy and stem

Trees may be small, medium sized or big at maturity. Some may grow just tall like

Eucalypt while others may even spread horizontally, usually denoted as huge e.g. Banyan. Some

trees may tower above the rest of the top canopy. There are termed as `emergents' Silk cotton

( Bombax ceiba) being a good example. The shape of the tree canopy (see Fig. 10) may be

described as erect (i.e. tall, not wide) like Eucalypt; semi-erect (semi-spreading) like Neem

( Azhadirachta indica) or spreading (umbrella shaped, rounded etc) like Mango ( Mangifera

indica). Some canopies may be dense like Jamun (Syzygium cumini) while some may be thin,

as in many Mimosaceae members like Acacia or Albizzia specie s. Most trees have alternate,

opposite or clustered branches from some distance above the ground, at an angle with the main

stem and pointed upwards (see Fig. 11). Some trees however may have horizontal and whorled

branches like the Kadamba ( Anthocephalus indica). A few may have branches drooping down,

the commonest example being the tall False Asoka ( Polyalthia longifolia) common in home

gardens. Some species considered here belong to the group known as Bamboos that have a

woody stem branching extensively right from the base. Some species are from the group of

palms which only have a few clustered leaves at the top and no branches, just the main stem.

Some tall tree species develop plank like supports at the base called buttresses (see Fig. 12) by

the upliftment of the roots from the soil followed by flattening e.g. Silk cotton tree ( Bombax

ceiba). Some trees do not have such buttresses but possess roots originating from the trunk,

travelling downwards and anchoring in to the soil. Trees with such stilt roots include members of

the Nutmeg ( Myristicaceae). Some trees may have a fluted trunk (see Fig. 13), some

cylindrical.

Bark

The bark texture (see fig. 14) could be rough or smooth and in some cases even glassy

like printing papers. Some trees have bark dotted with pores, termed as lenticels that probably


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felicitate gaseous exchange. Bark of some trees is cracked or fissured, in some cases only

marked with lines. Some species have bark falling off in irregular shaped pieces i.e. flakes. Some

species have pitted bark, depressions corresponding to fallen flakes. Barks also vary in colour,

gray being the commonest followed by brown, black, white, yellow, green etc. Barks thus

provide a great diversity and thus a useful mirror for distinguishing species. Bark features of a

species vary much more across individuals than the leaf characters. Nevertheless, features across

species are even more variable and hence, bark provides distinctive characters.

Leaves

Leaves are basically classified into two types – simple i.e. single and compound i.e.

group of leaflets (see Fig. 15). A leaf is often identified from the bud onwards, usually visible in

its axil. The bud may develop into a new leaf or shoot. The simple leaf has such buds right in the

axil of each leaf. In compound leaves, such buds exist only in the axil of a group of leaflets,

which many novices think as leaf. Further, the base of such compound leaves is usually

thickened for instance the Acacia or Neem. Sometimes the leaf and branchlet are identified from

the difference in colour and texture. Leaf is usually greenish and fleshy right from the petiole i.e.

stalk, the branchlet being brownish and woody. Some families like Euphorbiaceae have leaves

that with basal appendages termed stipules, to protect the buds. Stipules (see Fig. 16) may often

be small and scaly but occasionally large, leaf like stipules are seen as in the Bignoniaceae

family.

The leaves may be arranged alternate, opposite, subopposite or whorled (see Fig. 17). If

the successive pairs of opposite leaves have perpendicular orientation, these are termed opposite

decussate, like the Clusiaceae members. This minimises overshadowing and allows maximum

exposure to each leaf to light. Some trees like Jamun have such leaves on young branchlets but

on the older branchlets, the leaf orientation is the same i.e. they inhabit the same plane. This is

termed as opposite superposed arrangement. Some trees have subopposite leaves i.e. sometimes

opposite and otherwise alternate e.g. Celastraceae and Combretaceae members. Amongst trees

with alternate leaves a few species like mango have leaves closeted at the end of the branchlets

i.e. clustered arrangement.


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Shapes (see Fig. 18) and sizes of leaves are often characteristic for a species but differ

from one leaf to another or across trees. Characters like glands, small or texture (i.e. rough or

smooth, hairy or smooth etc.) remain relatively constant. Similarly, leaf tip (see Fig. 19) and leaf

base (see Fig. 20) characters vary more than the margin (see Fig. 21). The nervation is also a

peculiar character of not only species but even families (see Fig. 22). Stalk of the leaf, known as

petiole is also a characteristic feature, both when present or absent depending on the species. It

could be cylindrical or flat, channeled and/ or winged, thickened at the tip and/ or base,

sometimes even gland dotted, occasionally clasping the branchlet i.e. amplexicaule (see Fig. 23).

The petiolet i.e. the stalk of the leaflet may also show these characteristics.

Flowers and Fruits

The flowers may be singular or in bunches, called inflorescence, about which much

information is easily available in most taxonomic books, including in college curricula. The

flowers may arise from the leaf axils or from the branchlet terminals i.e. from the tip of the

shoots. While knowledge of shape and size matters a lot for a field identification, knowledge of

floral components is the basis of traditional taxonomy (see Fig. 24). The fruits also could be

simple or compound and dry or fleshy. While sizes and shape matter a lot to a field biologist,

biological classification is taxonomically important (see Fig. 25).

Confusing Taxa

Most tree species may be confused with one species or the other, at least prima facie.

Sometimes these confusing species may belong to the same genus and differ only minutely in

terms of leaves, flowers or fruits. However, species from entirely different genera or families

may also resemble in terms of general appearance, especially when viewed from a distance. The

book adds a line or rarely, an illustration in case of such confusing taxa. This has increased the

total number species referred in the book by a third of the species fully described. Some of the

confusing taxa are however fully described.

Diversity


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The figures of global species richness of genera and families are largely based on the

voluminous work by Cooke. The value at the global richness at the family level is cross referred

from the famous treatise by Lawrence. The figures for species richness in India have been

computed on the basis of the comprehensive volume by Brandis. The compact book by Santapau

on Genera of Indian flowering plants is also very useful.

The richness levels in the region covered i.e. Peninsular India, often but not always match

the figures for India. The discrepancy is common in case of genera inhabiting evergreen forest

and highlands, topography substantially represented outside besides within the peninsula. But the

figures for peninsular India, often exceed only marginally by those for the Western Ghats. These

have been refereed from the thesis on the Western Ghats endemic plants by Saldanha. The flora

of Tamil Nadu Carnatic by Mathew well represents the values and additions if any from southern

drier areas like Deccan. The flora of Rajasthan by Bhandari, represents the northern desertic

areas well.

Global Distribution

The distribution of taxa is described at two levels i.e. global and Indian. The volumes by

Cooke are an important source and so is the book by Santapau about genera of Indian plants. The

world distribution is basically divided into following categories (see Fig. 26).

a. Oriental – south and south-east Asia

b. Ethiopian – Africa and middle-east Asia

c. Tropical – The region around the equator and within the tropic of cancer in Asia,

Africa and America or atleast two of these continents. Often termed as `pantropical’

in the literature. Many species have been introduced from south America. Species

confined to South America are often termed as `neotropical’ while the species from

Asia and Africa are termed as belonging to the `old world’ or `Paleotropics’.

d. Temperate – The region between tropic of Cancer and Capricorn in either or both

hemisphere in any two continents.

e. Artict – The region between the poles and the tropic of Capricorn in either

hemisphere.


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Indian Distribution

The most comprehensive and advanced work on phytogeography of the Indian

subcontinent is by the French Institute of Ecology in Pondicherry, summarized in volumes by

Puri et al . Another classical work is that by Mani which largely reiterates the earlier schemes by

Hooker and his followers, mostly British.

Typically, peninsular India is the triangular landmass south of river Narmada that

penetrates into the sea. But the French Institute works suggest that floristically the region differs

a little from the plains remaining to the north till the Himalayan foothills. Thus, the definition of

peninsular India used by the French Institute and this book covers entire India except the

Himalayas. The area however excludes Andaman and Nicobar islands which have a rich but very

different flora akin to Malayasia and Sri Lanka.

Within this extended Peninsular India exist several floristic regions, chiefly as below (see

Fig. 1):

a. Western Ghats – The mountain chain running parallel to the west coast from Mumbai

to Kanyakumari, including the west coast and foothills on the eastern plains.

b. Eastern Ghats – The broken chain of mountains from Orissa in the north to Madurai

in the south, parallel to the east coast and within 100-200 km. of it.

c. Deccan – The drier plains of central Maharashtra, eastern Karnataka, western Andhra

Pradesh and central – southern Tamil Nadu. This southern most area may not be

typically included in the Deccan at least traditionally and may be assigned to

Tamilnadu (and/ or Carnatic) plains.

d. Rajasthan – The semidesertic areas of western Rajasthan and Gujarat, even western

Hariyana and Punjab, till the Himalayan foothills in Jammu and Kashmir.

e.

Central India – Traditionally confined to Madhya Pradesh and south Bihar. The latter

area hosts uplands popularly known as Chota Nagpur plateau. Added here are Uttar

Pradesh, Bihar and Bengal south of Himalayas, which have a similar flora. Much of

this area is traditionally termed as Gangetic plains and may perhaps even merit

consideration as a separate biogeographic zone from the point of view of grasses,


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sedges and aquatic life. However, it does not appear to have any different tree flora or

bird and mammalian fauna.

Besides Peninsular India and Himalayas proper , there may be considered a

phytogeographic region termed North-eastern India. This zone is difficult to define as it is hilly

and connected to Himalayas, allowing species influx and similarity. The area includes Assam

plains and Meghalaya, Tripura hills. The mountains from Manipur and Nagaland rise much

higher and directly connected to Himalayas and thus have much the same biota. It may be

included in Eastern Himalayan phytogeographic zone.

Climate and Altitude

Based on the bioclimatic scheme proposed by the French Institute in the book by Puri et

al, following classes have been adopted here, within Peninsular India


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Bioclimate Average

Annual

Rainfall

(mm)

Length

of Dry

Season

(months)

Altitude

above sea

level

Temperature

mean annual

°C

Typical

Regions

Hot and

semi-arid

200-500 8 - 10 0-400 25 Rajasthan

Hot and dry 500-1000 7 - 9 0-1000 22 Central India,

Deccan

Hot and moist 1000 – 2000 5 - 7 0-1000 20 Eastern Ghats,

West Coast

Hot and Humid 2000-7000 3 - 6 0-1500 20 Western

Ghats, N. E.

India

Cool and Humid 1000 – 6000 1 - 6 1500-2500 15 W. Ghats

(Nilgiri,

Palani,

Bababudan)

In the Western Ghats region, the French Institute has suggested the following

classification of altitudinal zones, which appears broadly applicable –

Low elevation : 0 to 800 m asl

Medium elevation : 800 to 1500m asl

High elevation (montane): 1500 to 2500 m asl.

Habitat Typology

The kind of places inhabited by an organism and described under the term habitat. The

habitat classification is described at three scales there –


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a. VEGETATION TYPE – at the scale of hectares. This includes following vegetation

types (refer Fig. 2). The species characteristically inhabiting or even defining these

habitat types are mentioned in Table 1.

1. Forest – group of trees with canopies meeting and covering over half the ground.

Often termed as woodlands in old popular books. Divided into evergreen,

deciduous and semievergreen (mixed) categories based on leaf shedding habits of

majority of trees.

2. Scrub – group of shrubs, often thorny and densely packed, with a few scattered

trees.

3. Savanna – scattered trees interspersed with grasses, herbs or shrubs. Often termed

as woodlands in ecological classification.

4.

Plantations – These include the traditional `forestry’ plantations like teak and

Eucalypt with a lot of natural regeneration due to proximity to forests. It also

includes social forestry plantations like that of Australian Acacia, and Eucalypt,

often along the avenues and in fallow lands, wastelands, often away from the

forest and devoid of natural regeneration. Similar are intensively managed private

tree crops of Arecanut, coconut, rubber etc. often termed as `orchards’, which are

also included here under the class `plantations’.

5. Human habitation – This is a very heterogeneous vegetation type in terms of

canopy cover and composition. It includes home gardens, yards of public places,

urban or rural avenues besides the field bunds.

b. STRATUM – at the scale of tens of meters. This primarily describes the place of a

species in the vertical stratification of the vegetation such as :

Upper canopy : 20 – 30m

Middle canopy : 10 – 20m

Lower canopy: 5 – 10m

Undergrowth: 0 – 5m


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c. HABITAT – at the scale of few tens of meters. These include banks of watercourses,

valleys and such moist places, sunny areas like canopy openings and open places

devoid of dense vegetation, eroded sites, rocky scarps etc.

d. NICHE- at the scale of few meters. The habitat preferred by the species reflects its

ecological role. For instance, pioneer i.e. early successsional species mostly prefer

sunny area like canopy gaps or even degraded vegetation and eroded sites like rocky

outcrops. On the other hand, the climax species usually prefer moist, shady localities

such as stream banks and valleys.

Animal Interactions

Information on this vital aspect is most interesting but unfortunately, most wanting. Few

cases described here like in the case of Shorea robusta are only illustrative and intended to rouse

curiosity of the readers to look for more such interactions in the life around. Trees depend a lot

on several insects, particularly honey bees for pollination and in return even provide them with

shelter, besides nectar. The information on this aspect of pollination is relatively better thanks to

the efforts of the Central Bee Research Institute. The trees also depend on several animals

particularly birds and mammals for dispersal of seeds. Many tree species thus invest in making

their fruits fleshy, seat smelling and attractively coloured. Much less is known about this aspect

than could be generated through curious birdwatchers that fail to identify the host species

providing birds the food or shelter, in the absence of user friendly fieldguides.

There is yet another kind of intricate relationship that trees enjoy with insects like

butterflies by serving as their larval food plants. Specific butterfly species lay their eggs only on

particular tree species so that the emerging larvae get the requisite plant chemicals. This includes

for instance, the butterflies from the milkweed (Dannideae) family that raise their larvae on

leaves of plants from Apocynaceae and Aesclepiadaceae families, both having milky latex. The

butterflies thus have a bitter taste from the viewpoint of birds, which show a marked disinterest

in hunting and consuming not only milkweed butterfly species but their mimics from otherwise

edible families! Some information on butterfly host species exists in the classical book on Indian

butterflies by Winter Blyth and some more vital bits are added by Kunte of late. Lastly, one


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cannot overlook the information packed volume by Stebbins on Indian forest insects. It is

however confined primarily to insect pests of the timber trees but aspects like life history are

attractively.

Seasonality

As a rule, most peninsular Indian trees, including the evergreens shed their leaves during

spring i.e. January – February. Many deciduous trees become fully bare while the evergreens

retain much of the leaves. This is followed by the flowering bloom during March – April. Some

deciduous trees are in full bloom when completely devoid of leaves such as the `flame of the

forest’ ( Butea monosperma) and the Amaltas/ Bahava (Cassia fistula). These are no doubt

amongst the most beautiful trees of the land. Leaf shedding is not markedly higher in the

ever-wet tropical forests of south-east Asia termed rainforests. However, the peak litterfall

observed in Indian evergreen forests such as in the Western Ghats during these months could

only be attributed to a longer dry spell, lasting 3 to 6 months, resulting in marked soil moisture

deficit. End of summer marks the new flushes of leaves, often with reddish tinge. The leaf

flushing before the monsoon and moisture deficit saturation provides the opportunity for optimal

leaf growth before the insect load increases during the monsoon. This is accompanied by

development and even maturity of fruits, allowing seed dispersal just before the rains begin. This

is particularly true of species having a very short seed viability of a week or two. A classical

example is the famous timber tree of northern India, the sal (Shorea robusta), which is confined

to regions with certainty of arrival of rains within a fortnight of seeding time of the species,

during mid June.

Interestingly, the distribution of the timber tree of southern India, the teak (Tectona

grandis) i s also determined by climatic seasonality. This species flowers during the rainy season

i.e. August – September. The French Institute hypothesises that the species was common in the

drier areas like Deccan but uncommon in the adjoining Western Ghats where the heavy rainfall

might wash away the flowering. Much of the Teak trees in the Ghats are indeed planted, since

British times. Trees like Teak have seeds with a hard coat which must be exposed to rain and sun

over long period to enable the embryo to break open the weakened seed coat. Thus, such seeds

usually fall well before the rains entailing wait for a few months or even an year to germinate.


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Human Significance

Trees yield several useful products such as timber, edible fruits, fodder for cattle, manure

from leaves and branchlets, medicines from roots, bark, flower and fruits etc. Though number of

such uses have been recorded in the CSIR book as also in the book by Talbot, it remains to be

seen whether many of these uses actually persist in rural life today. There are however fairly

recent examples of trees like Hardwickia binata having provided fodder to scores of hungry

cattle during famines, when grass availability had dropped drastically.

Population

Population assessment of most tree species has never been attempted scientifically and

remains a task immensely difficult in the field. Nevertheless, based on the first hand experience

of a few quantitative sampling programmes in the Western Ghats and Central India, following

categories have been evolved to describe the density levels of tree species per ha

Abundant: 10 – 100

Common: 1 – 10

Frequent: 1

Occasional/ infrequent: 0.1 – 1

Rare: 0.01 – 0.1

The estimates of a given population i.e. isolated group of trees can be derived by

multiplying these density levels with the area of the population. Thus, abundant species will have

a population of 100 to 1000 trees while rare species barely one tree in an area of 10 ha. However,

it is assumed that the densities refer to homogeneous population and not to irregular or clumped

distribution of trees.

Conservation

This section briefs about the population decline or threats and suggested measures for

restoration, besides habitat preservation, if any. It begins by a note on regeneration frequency

employing terms like the population density levels. The numbers involved however are several

times the tree density values, given the small size of the saplings compared to trees. The lack or


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rarity of regeneration is no immediate signal of future population decline as different species

may exhibit different regeneration strategies including small tree to sapling ratio.

Some species exhibit r-life history strategy. Small sized and/ or pioneer trees, including

Bamboo often show this strategy involving explosive and even episodic regeneration. These

produce numerous offsprings especially under favourable conditions like the canopy gaps

preferred by the pioneer species. The sapling mortality may be high and the population may

eventually decline as the individuals grow larger, as postulated by the self-thinning law of

plantations. Some examples may include the commonest of the forest trees like Garcinia, a shade

loving tree and Macaranga peltata, a pioneer in the evergreen forests. Yet others may follow

contrary life history pattern known as k-strategy. These regenerate very scantily but juvenile

morality is very low. Some light demanding species germinate in the shade and wait for years till

a canopy gap appears overhead. Upon this, the saplings grow very speedily. Their population

dynamism is best explained not by law self thinning densities but by `wait and watch' model.

Some examples include the emergents like Mango or Silk cotton trees.

The regeneration may mostly occur from seeds but a few species also multiply from root

suckers, such as the famous sal tree. The saplings and trees grown vegetatively may be

genetically clones of i.e. nearly identical to the mother trees. Population of such coppice trees is

thus genetically inferior to sexually reproduced trees. This could have disastrous consequences.

Most of the Sal forests from central India have been the result of coppice growth encouraged due

to operational ease by the forest department over years, especially in areas heavily felled for

timber. But these dense, lush green stands of such coppice forest resemble monoculture that too

genetically homogeneous. So a particular strain of pest like woodborer easily sweeps through the

entire crop killing the whole stretch of trees.

This is evident in periodic attacks of Sal borer beetles in Madhya Pradesh especially

around Mandla district once in every two or three decades, which are ensured by emphasis on

coppice regeneration. The Sal seeds are collected from the forest floor to yield the chocolate fat.

Thus low soil seed store favours coppice regeneration over seed germination. On the contrary,

the less harvested, more naturally, sexually regenerating forests of Kanha National Park in the


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same district show much less intensity of the insect attacks. The clear message is that the

vegetative propagation including the high tech tissue culture could be an efficient, easy technique

but does not guarantee diversity and ong term conservation. Habitat preservation approach

ensuring natural reproduction has no match.

Besides such fluctuations, there occur marked population decline or incline in a few

species, primarily due to direct human influence. The trees of Xylia xylocarpa for instance, were

suddenly felled in very large numbers at the turn of the century for railway sleepers. At the same

time enormous plantations of Teak were raised throughout India, including in the Western Ghats

where the species was not common. Much of the plantations of Leucena in India suddenly

succumbed pest during the last decade, when a the pest from its home, southeast Asia invaded

India a few years after the tree was introduced. A study of such population changes is an

important consideration affecting conservation decisions besides regeneration strategies.

Adaptations

Evolution is an ongoing process, having lead to such diversity of life. Evolution and

adaptations are known to be quicker in organisms with shorter life span such as insects that

constantly evolve to predate on host plants. The plants also evolve to minimize the insect

damage, by adding chemicals of various kind to their armour, though the rate of adaptation is

slow. In fact, it is believed that evolution of much of the plant diversity in the tropics can be

attributed to heavy insect load and diversity as compared to the temperate regions. However, all

adaptations are not necessarily due to conflict, some are geared to promote cooperation such as

in the plant-pollinator relationship. Thus, some trees may produce flowers with special shapes,

offering a comfortable seat to the bees. Yet others like Humboldia species exhibit hollow

channels running all along the stem, inhabited by specific ants. The aggressive ants protect the

tree from other insects while ants are rewarded with shelter and honey from extrafloral nectar

glands, possibly an adaptation. Most interesting is the case of evolution of fig trees to attract

pollinator wasps, as described by Ganeshaiah et al.

The trees adopt not just for animal interactions but also in response to environmental

constraints or opportunities. Most of the tall, emergent tree species of forest canopy have


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developed huge buttresses at the base to avoid wind-throws. Trees from Elaeocarpaceae and

Myristicaceae family often posses adventitious i.e. stilt roots that anchor the tree base to the soil.

Some like Lophopetalum wightianum have roots that run horizontally just beneath the soil

surface and form a dense mesh several meters wide. These are adaptations for loose, moist soils,

the preferred habitat. Some adaptations may be indicators of evolutionary changes . Carallia

brachiata, a tree from the family Rhizophoraceae occasionally shows stilt roots emerging from

beneath the lower branches. This is the one of the two tree species found inland while the rest of

the species from the family inhabit coastal mangroves. The current habitat of Carallia, the

evergreen forests away from tidal zone, does not necessitate stilt roots for anchoring of trees. But

the rudimentary feature probably suggests the original habitat of the species – the swampy,

marshy soils, even coastal.

Projects

The bane of natural history in India is perhaps excessive emphasis or rather, restriction of

biology education within the four walls, primarily laboratories full of dead specimens. If the

students should become more observant, analytical and active, learning in the live laboratory of

nature outside the four walls is a must. To encourage such curiosity, some understanding,

unmatched satisfaction from `do it yourself’ approach; several interesting field experiments are

suggested regarding some species and some general experiments for community of species.

These projects could advance understanding of not just the habitat preference but also

evolutionary adaptations, ethnobotany, species interactions etc.

The projects may be undertaken by anybody interested, not necessarily a formal school or

college student. Unfortunately there is no network today to share the results and suggest

innovations, modifications etc. However, such platforms will become gradually available. To

begin with, journal Resonance of the Indian Academy of Sciences might publish deserving

observations and thoughts under its Lifescape series. Even if few people begin experimenting

along these lines, days may not be far away when tree-watcher's clubs dot the country, like sports

or youth or bird-watcher's clubs at present


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Provided below are some ideas about such general projects at a general level. Some of

these are specifically suggested in the discussion of individual species, but the similarity in

behaviour of several species along number of dimensions makes it difficult to suggest species

specific projects such as the study of Sal wood borer insect. Another difficulty in suggesting such

species specific projects is lack of adequate information on animal interaction and other

ecological aspects of most species. For, much of the information gathered during the British

regime pertained to timber properties of pests harmful to timber. Later, hardly any ecological and

otherwise interesting information was generated, except some ethnobotanical research, again due

to its applied value. The projects can be categories as below:

Niche, guild occupancy:- Attributes such as pollination and dispersal mechanisms, stress

resistance of pioneer and climax species can be compared. Also could be compared species

dominating different vegetation types like scrub and forest. For instance, the same species is

often known to have thicker bark than the scrub or savanna vegetation than forests where the

environmental stress like fire is lower, unlike savanna, as studied by Hegde et al, an M.Sc.

student project.

Seasonality impacts:- Sal distribution is supposed to be restricted to areas where rainfall arrival

dates do not exceed 10 days of the fruit fall due to low seed viability. Students from these areas

can actually keep track of annual rainfall and fruit fall dates. Besides, they may also maintain a

regeneration index to see if the regeneration indeed drops in years with late monsoon.

Phenology:- Besides regular records of flowering, fruting periods, special phenomenan like

masting i.e.above average production of flowers and fruits after a lapse of few years, often

observed in case of Dipterocarpaceae members can be monitored alongwith rainfall records.

Mango farmers also know this process and their wisdom can also be gathered. Phenology

monitoring every month could help in speculating the fate of Fig trees that ostensibly depend on

pollinator wasps which in turn cannot live outside the floral cup of specific fig. Thus if no fig

trees of a species are in flowering during any given season, the wasps have to either perish or

migrate in nearby landscape, not more than a few kilometers away in search of flowering trees. If

they migrate, trees do not get pollinated and fail to produce seeds, hampering regeneration next


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year. If they perish, trees cannot produce seeds unless wasps from neighbouring landscapes

invade and pollinate them. For more details, see article by Utkarsh and Almeida.

Forest dynamics:- Assessing mortality and regeneration rates of various tree species in nearby

areas, especially from the periodic records of the forest department on preservation plots, is an

interesting exercise, also of applied value in forestry. It is important to test if the pioneers have

higher regeneration, growth and mortality than the climax species, as may be expected. The

regeneration and mortality rates are known to be generally lower in stress affected sites like

fire-prone forests, which could be locally verified.

Tree growth:- Rates of growth of individual trees and species, in relation to age and habitat

conditions, based on data as above. It could be tested if pioneer species have higher growth rates

than the climax species as generally believed.

Harvest impact :- Regeneration or coppicing vigour for trees of species harvested for fruits or

fruiting branches, in harvested and unharvested areas or trees. Studies on Gooseberry

( Phyllanthus emblica) trees by Ganeshaiah et al. are illustrative. Similar studies can now target

Garcinia species from the Western Ghats or Mahua and Sal trees from central India, where these

species critically contribute to rural income.

Density regulation:- Regeneration or size frequencies at increasing distance from large/r/st trees

of focal species to see effect of mother tree on saplings. Pioneers species like Silk cotton with

long distance dispersal ability are expected show scattered regeneration, not necessarily clumped

near the mother tree. Opposite could be the case of climax species like Garcinia that have heavy

fruits and seeds, falling and regenerating near the mother tree, unless dispersed widely by

animals.

Competition:- Effect of invasion of weeds like Lantana or Eupatorium on density/ protection/

shadowing of regeneration of other species in areas with invasion of different size/ age. It would

be important to observe if such exotic species may be eventually edged out by the local species

in the absence of human influence as in the protected areas. The weeds may also outsmart local


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species as is generally observed in areas with high human influence like in the roadside

vegetation where dispersal agents like cattle frequent. Comparison of pollination and dispersal

characters as well as predatory pressure on weeds and local species proves illuminating.

Sibling rivalry:- Size of seeds in relation to number per fruits across species or growth and

mortality of saplings over two three years in small plots with ample regeneration of focal species

raises appealing questions and unique opportunities.

Reproductive allocation:- Relation of average leaf size to individual's age/ fruiting vigour.

Younger plants like saplings generally have higher average leaf size than the older trees of the

same species. Perhaps, this allows capturing more sunlight at a young age through limited leaves

available. On the contrary, older plants invest more in flowers and fruits to ensure the future

generation rather than maximising their own profits like tapping more sunlight.

Symbiosis:- Keeping records of identity, frequency and activities of birds and mammals visiting

focal species could not be a means to gain pride in Birdwatcher's clubs but also have great

applied value to reforestation. Detection of nature and intensity of soil mycorrhiza near and away

from trees especially from Dipterocarpaceae family is an interesting research line, much pursued

in South East Asia where such forests abound.

Commensialism:- Choice of host trees for bee combs, relative importance of floral resource

proximity or barriers like tree height, canopy isolation etc. Some trees like Silk cotton and

Tetrameles nudiflora that typically shelter colonies of such beehives could constitute interesting

living laboratories provided care is taken to avoid bee attack.

Prey-predator :- Equally useful is the study of tree mortality and predator population intensity in

case of pairs like the Sal and its wood-borer and other case described in Stebbin's book. Another

interesting feature is predation of the predator such as the parasitic wasps or beetles feeding on

wood borer of Sal. At what density of the wood borer or under what environmental conditions

does the population of parasites springs up? When does it fall, with reduced host densities?


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Parasitism:- Incidence of parasites like Loranthus or Viscum or epiphytes Fig trees, host

choice, relation to species, age/ size, soil, effects on fruiting vigour etc. Does parasite infestation

increase with logging or cutting of branches, exposing the inner tissues and providing

colonisation site for the parasite? Does fig epiphyte density decline with disturbance as observed

in some tropical forests or the reverse happens in India, as observed in rural and urban areas

abounding in epiphytic figs in contrast to forests?

Technical Terms

Technical jargon has been avoided to the extent possible without compromising adequate

description of the facts. The technical terms are used only when utmost necessary, and explained

in the glossary section.

Contributions

The book of course is the result of efforts a large team. However, due to the space

shortage; each taxonomic account acknowledges only a few lead names involved in writing,

reviewing, illustrating etc.


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BIBLIOGRAPHY

(being updated and completed)

Ali Saalim. 1942. The book of Indian Birds. Oxford.

Anon. 1975. Common Indian Trees. Council for Scientific and Industrial Research. New Delhi.

Balsubramaniam et al. 1986. Field key to the indigenous trees of Kerala. Kerala Forest Research

Intitute. Peechi.

Bhandari. 1970. The Flora of Rajasthan Desert.

Blatter. E. 1950. Beautiful Trees, Shrubs, and Climbers of India. Oxford.

Bole. P. R. and Y. Vaghani. 1986. Fieldguide to common trees of India. Oxford.

Brandis. D. 1978. Indian trees. Bishen Singh Mahendra Pal Singh. Dehradun.

Chandran, M. D. S. 1996. Ecological history of the Western Ghats. Current Science. Spl. Issue

on biodiversity.

Cooke. T. 1975 (repr.). Flora of Bombay (3 vols.) Bishen Singh Mahendra Pal Singh. Dehradun.

Dixit S. P. 1997. Scientific names of plants explained. Disha Prakashan. Nasik.

Ganeshiah K. et. al.. Evolution of Ficus.

Hegde et al. 1999. Bark thickness of tropical trees: A case study from the Western Ghats.

Hooker J. D. 1985 (repr.) A sketch of Indian Flora. Bishen Singh Mahendra Pal Singh.


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Kunte K. 2000. Fieldguide to common Indian butterflies. Indian Academy of Sciences.

Bangalore.

Lawrence. H. M. 1957. Taxonomy of flowering plants. Oxford.

Mani. M. 1974. Ecology and Biogeography in India. W. Junk The Hague.

Mathew. K. M. 1992. Flora of Tamilnadu Carnatic (4 vols.) Rapinat Herbarium. Tiruchirapalli.

McCann. C. 1950. Common Indian Trees. Bombay Natural History Society. Mumbai.

Nayar. M. P. 1985. The meaning of Indian Flowering Plants. Bishen Singh Mahendra Pal Singh.

Dehradun.

Pascal. J. P. 1988. Vegetative key to trees and lianas of the wet evergreen forests of Western

Ghats. French Institute. Pondicherry.

Puri et. al. 1988. The wet evergreen forests of Western Ghats. French Institute. Pondicherry.

Randhawa 1985. Beautiful Indian Trees.

Rheede Van. 1986 (repr.). Hortus Malabaricus. Bishen Singh Mahendra Pal Singh. Dehradun.

Sahani. K. C. 1999. A book of Indian trees. Bombay Natural History Society. Mumbai

Saldanha. C. J. (unpubl.) Endemic flowering plants of Western Ghats. Centre for Taxonomic

Studies, Bangalore.

Santapau H. 1970. Genera of Flowering plants of India.

Santapau H. 1970. Common Indian Trees. National Book Trust. New Delhi


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33

Stebbins. 1980 (repr.). Forest flora of Indian forest insects. Bishen Singh Mahendra Pal Singh.

Dehradun

Talbot W. A. 1975 (repr.). Forest flora of Bombay Presidency. Bishen Singh Mahendra Pal

Singh. Dehradun

Utkarsh G. and Almeida, M. R. 1999. Genus Ficus. Resonance.

Whitemore, T. C. 1975. A field key to identification of Malayan tree flora.

Winterblyth M. A. 1986. (repr.) A book of Indian Butterfly. Today and Tommorrow Printers and

Publishers. Delhi.


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LIST OF FIGURES

1. Phytogeographic regions of India

2. Side view of various vegetation types

3. Tree, shrub and herb profile

4. Basal shoots

5. Litter dynamics- spread and depth

6. Leaf glands- surface, margin, petiole

7. Taxonomic hierarchy

8. History of introduction of Sandal/ Coconut in India

9. Deciduous, Semievergreen and Evergreen canopy

10. Erect, Semierect and spreading canopy

11.

Branching pattern- normal, horizontal, drooping, whorled

12.

Buttresses, Stilt roots

13. Trunk- cylindrical, crooked, fluted

14. Bark- lenticelled, lined, pitted, flaky, fissured, crocodile

15. Leaves- simple, compound, subtypes

16. Stipules- scaly, leaflike

17. Leaf arrangement- opposite, subopposite, alternate, clustered, digitate

18. Leaf shapes

19. Leaf tips

20. Leaf bases

21. Leaf margins

22. Nervation patterns

23. Petiole types- sessile, thickened, glandular, channeled, winged, amplexicaule

24. Floral components

25. Fruit Types

26.

Global distribution categories


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ANNEXURES

1. Field identification key to the trees covered in the book.

2. Species with very distinguishing identification characters like gregarious, colourful flowering

or peculiar fruiting etc.

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