INFLORESCENCE, POLLINATION AND FERTILIZATION

Prepared to meet the task Structur and Development of Plants 1

ARTICLE

By

Niswati Zahro

NIM 100210103068

PROGRAM STUDY EDUCATION SCIENCE OF BIOLOGY

FACULTY OF TEACHER TRAINING AND EDUCATION

UNIVERSITAS JEMBER

2011

INFLORESCENCE, POLLINATION AND FERTILIZATION

Niswati Zahro

(100210103068)

ABSTRACT

Before plants was die, usually it will produce a component that will become new

plant called flower. Inflorescence is the arrangement of a group of flowers borne

on the same main stalk. In a racemose (or indefinite) inflorescence the tip of the

main stem continues to grow and flowers arise below it. Flower have many part to

support fertilization and pollination even to form fruit that have seeds.

Pollination is the process by which pollen is transferred in plants, thereby

enabling fertilization and sexual reproduction. Pollen grains, which contain the

male gametes (sperm) to where the female gamete(s) are contained within

the carpel. Fertilization is fused even of ovum and sperm after pollination.

Key word: inflorescence, pollination, fertilization, fused

1. Introduction

Plant reproductive organs differentiated into 2 groups, namely generative

reproduction and vegetative reproduction. Generative organs has a shape and

arrangement of which varies according to species of plants, but spermatophyta,

commonly referred to as a flowers. Therefore, a plant seed, if it is time to

reproduce flowers. There are two types of flowering is a single flowering (planta

uniflora) and compound flowering (inflorescentia). In a planta uniflora, only

supports a single flower stalk, while the inflorescentia, a flower stalk to support

many flowers. Inflorescence should be distinguished from the branch that

supports some of flowers in axillary, but not easy to distinguish a compound

interest from the branch that has the flowers in axillary leaves (Tjitrosoepomo,

2009).

Flowers is the plant’s organ which will become fruit and in fruit, seed will be

happening in there potential make a new plant that is cotyledons. Fruits, seeds and

cotyledons will occur after the first event pollination and fertilization

(Tjitrosoepomo, 2009). Reproductive parts are located within the flowers. Plants

may be unisexual or bisexual, i.e the male and female reproductive parts located

within the same flower or on separate flowers. The male reproductive organ is

known as Androecium while the female is known as Gynoecium. The

Androecium is composed of stamens that is made of up a filament and anther. The

anther contains pollen sac that produces pollens. Male gametes are contained

within the pollens. Both gymnsosperms and angiosperms belong to the

spermatophyta or flowering plants family, the difference being mainly how the

seed are borne. However, the pollination and fertilization mechanisms, though

similar in actual context also have differences (Sengupta, 2010). Based on the

above background, it is necessary to do a study to add insight the students to

better understand inflorescence, pollination and fertilization events.

2. Inflorescence

Flowers may be born singly on plants, when they are said to be solitary, or they

may from clusters. Such clusters of flowers, together with the stems and bracts

associated with them, are called inflorescences. Some flowers heads are extremely

complex, expecially in the grasses and in the family to which the dandelion and

daisy belong, each head consisting of many dozen or even hundreds of individual

flowers (Sengupta, 2010)..Compound.flower has the parts.that are like the

stem, like.a.leaf, as.well.as parts.if atypical flower, like.a crown of.flowers, pistil,

and benangsari.The parts that are like stem, for example:

a) Main flower stalk (peduncle, pedunculus), which is the main which supports.

whole compound flowers.

b) Section mother flower stalk inthe middle.of the.inflorescence,in which.the indi

vidual flower stems attac.ed, called.the rachis (rachis)..Flower stalk (pedicel, p

edicellus), the stalk of.each individual flower

c) Basic flower (receptacle, receptaculum), base of flowers stalks that support

other parts of flower. (Sengupta, 2010).

The parts are like a leaf, for example (Dillon, 1964):

a) Protective leaf (bractea), leaf likes the main axillary leaf

b) Leaf stalks (bracteole), that is leaves (1-2 leaves) that appear on base

flower stalks.

c) Flower sheath (spatha), leaves are larges shield that surrounds the whole

compound flowers prior to bloom, for example on flower Palm palmae.

d) Leaf pads (involucrum), an amount of protective leaves arranged in a

circle around the compound flowers basis, for example in the Hellianthus

annus L.

e) Leaf additional (epicalyx), an around of protecetive leaves arranged the

petals for example in Hibiscus rosa-sinensis.

f) Sepal

g) Petal

h) Tepal

i) Stamen

j) Pistil

Generalized parts of flower

3. Type of Inflorescences

Based on bud growth, the introduction of monopodial growth and simpodial. Two

kinds of growth were also reflected in the growth of flower:

1. Compound flower is limited growth (inflorescentia cymosa) that is compound

flower who stalks is always covered by a flower, so the main stalks has

limited growth. Flowers that bloom first is contained in the main flower stalks,

so from the middle to the edge. Base of branches in the main stalk, compound

flower bounded distinguished into three kinds ( Tjitrosoepomo, 2009):

a) Monochasial, if the main stalks has only one branch stems, there are

two branches but never confronted and which one is larger than the

other branches

b) Dichasial, if at the main stalk rise out of two branches dealing

c) Pleiochasial, if the main stalk rise out more than two branches at the

same height somewhere on the main stalk.

2. Compound flower is unlimited growth (inflorescentia racemosa), compound

flower that main stalks can continue grow branched which can be branched

again and have acropetal arrangement (the younger flower closer premises

main stalk and flower bloom from bottom to top.

Pleiochasial cyme

Kinds compound.interest limitless with nobranching on main stalk (Sengupta,

2010) :

Spike

A Spike is a group of flowers arising

from the main stem, without

individual flower stalks (sessile).

The example is Agastache

foeniculum.

Raceme

A Raceme is a flower spike where the

flowers have stalks of equal length,

and the tip of the stem continues to

grow and produce more flowers.

Flowers open from the bottom up.

The example is Linaria vulgaris.

Panicle

A Panicle is a branched raceme, each

branch having a smaller raceme of

flowers. The terminal bud of each

branch continues to grow, producing

more side shoots and more flowers.

The example is Lagerstroemia indica.

Cyme

A Cyme is a group of flowers in

which the end of each growing point

produces a flower, so new growth

comes from side shoots and the oldest

flowers are at the top.

The example is Geranium pratense.

Verticillaster

A Verticillaster is a whorled

inflorescence, where the flowers are

borne in rings at intervals up the stem.

The tip continues to grow, producing

more whorls. This type of

inflorescence is common in members

of the Deadnettle/Mint Family

(Lamiaceae).

The example is Phlomis russelliana.

Corymb

A Corymb is a flower cluster where

all the flowers are at the same level,

with flower stalks of different lengths,

forming a flat-topped flower cluster.

The example is Achillea millefolium.

Umbel

An Umbel is a flower head in which

all the flower stalks are of the same

length, so that the flower head is

rounded like an umbrella. Many bulbs

have this type of flower head.

The example is Nerine bowdenii.

Compound Umbel

A Compound Umbel is an umbel

where each stalk of the umbel

produces a smaller umbel of flowers.

This type of inflorescence is typical of

members of the Celery Family

(Apiaceae).

The example is Crithmum maritimum.

Capitulum

A Capitulum is a flower head

composed of many separate unstalked

flowers close together. This type of

inflorescence is typical of the Daisy

Family (Asteraceae), where the outer

flowers have one conspicuous large

petal and the central disk is formed of

flowers with smaller petals.

The example is a Senecio species.

Like everything else in nature, these descriptions can only be a general guide to

how your flowers might look. There are many variables, even on one plant, and

flower clusters are often described as raceme-like cymes, or cymose panicles, or

other words that indicate that the flowers do not conform exactly to any one type

of inflorescence. The habit of growth may also be affected by growing conditions,

so something that produces clear whorls in moist conditions might produce

flowers closer together to form a denser spike in drier conditions. I generally refer

to anything in long, thin inflorescences as a spike, and anything more rounded as a

cluster (Curtis, 1968).

3. Mixture of compound flower (inflorescentia mixta), that is compound

flower who shows good properties as well as the nature of compound

flower limited and compound flower limitless (Marsland, 1964).

4. Reproduction in the flower

Pollination and fertilization are the two processes that aid in plant reproduction.

These two processes are indeed different from each other, but are interconnected

with each other. Pollination is the first step preceded by fertilization that finally

leads to formation of plant zygote. A successful pollination leads to fertilization.

Significant differences are observed on comparing pollination vs fertilization. But

before doing the in depth analysis of the difference between pollination and

fertilization in plants, we must know the basic structure of plant reproductive

system (Marsland, 1964).

4.1 Gynoecium

The gynoecium consists of the stigma, style, and ovary containing one or

more ovules. Stigma- the stigma is female part of the flower. This is where the

seeds are made. The stigma is sticky to catch the grains of pollen. The style is the

neck that the pollen travels down to get to the Ovary. I n the ovary, the pollen

joins the ovule and the ovules become seeds. The Receptacle is the top of the

flower. These three structures are often termed a pistil or carpel. In many plants,

the pistils will fuse for all or part of their length (Marsland, 1964).

The female reproductive part or Gynoecium is composed of one or more pistils.

Pistil contains carpels and carpels house ovary and ovules. Female gametes are

located inside ovules. Pistil has three parts namely stigma, style and filament. The

stigma forms the receptor of pollen grains that is supported by stalk. The pollen

grains pass through the style, filament and finally reaches the ovule. The ovary

contains one or more ovules, which in turn contain one female gametophyte, also

referred to in angiosperms as the embryo sac. Some plants, such as cherry, have

only a single ovary which produces two ovules. Only one ovule will develop into

a seed (Marsland, 1964). .

4.2 Stamen

Stamen are the male parts of the flower. They make the pollen. Pollen is the fine

yellow powder needed to make a new plant. Each stamen has two parts, the

anther and the filament. The anther contains the pollen and the filament holds up

the anther (Stein, 2010).

a. Filament

b. Anther, discharging pollen

5. Pollination

When the pollen is fully developed, the pollen sac breaks in manner already for

transfer to the stigma. Whether the transfer (called pollination) is accomplished by

wind or water or by activities of insect or birds, the important feature here is that

it reaches a ripened stigma, i.e., one that the fully matured and ready for

pollination (Dillon, 1964). Pollination is the process by which pollen is transferred

in plants, thereby enabling fertilization and sexual reproduction. Pollen grains,

which contain the male gametes (sperm) to where the female gamete(s) are

contained within the carpel; in gymnosperms the pollen is directly applied to the

ovule itself. The receptive part of the carpel is called a stigma in the flowers of

angiosperms. The receptive part of the gymnosperm ovule is called themicropyle.

Pollination is a necessary step in the reproduction of flowering plants, resulting in

the production of offspring that are genetically diverse (Marsland, 1964).

Based on the origin of pollen which on the stigma, pollination divided into

several types, that is:

1. Self-pollination . Self-pollination occurs when pollen from one flower

pollinates the same flower or other flowers of the same individual.[9]

It is

thought to have evolved under conditions when pollinators were not

reliable vectors for pollen transport, and is most often seen in short-lived

annual species and plants that colonize new locations. Self pollination may

include autogamy, where pollen moves to the female part of the same

flower (Marsland, 1964).

a. Geitonogamy, when pollen is transferred to another flower on the same

plant. Plants adapted to self-fertilize often have similar stamen and

carpel lengths. Plants that can pollinate themselves and produce viable

offspring are called self-fertile. Plants that cannot fertilize themselves

are called self-sterile, a condition which mandates cross pollination for

the production of off spring (Marsland, 1964).

b. Cleistogamy: is self-pollination that occurs before the flower opens.

The pollen is released from the anther within the flower or the pollen

on the anther grows a tube down the style to the ovules. It is a type of

sexual breeding, in contrast to asexual systems such as 12pomixes.

Some cleistogamousflowers never open, in contrast

to chasmogamous flowers that open and are then pollinated.

Cleistogamous flowers by necessity are self-compatible or self-fertile

plants. Many plants are self-incompatible, and these two conditions are

end points on a continuum (Marsland, 1964).

2. Cross-pollination, also called allogamy occurs when pollen is delivered to

a flower from a different plant. Plants adapted to outcross or cross-

pollinate often have taller stamens than carpels or use other mechanisms to

better ensure the spread of pollen to other plants' flowers (Marsland,

1964).

3. Hybridization is pollination between flowers of different species, or

between different breeding lines or populations. (Marsland, 1964)

Pollination syndromes are suites of flower traits that have evolved in response

to natural selection imposed by different pollen vectors, which can be abiotic

(wind and water) or biotic, such as birds, bees, flies, and so forth. These traits

include flower shape, size, colour, odour, reward type and amount, nectar

composition, timing of flowering, etc. For example, tubular red flowers with

copious nectar often attract birds; foul smelling flowers attract carrion flies or

beetles, etc.(Curtiz, 1968)

1. Wind pollination (anemophily)

Flowers may be small and inconspicuous, green and not showy. They produce enormous

numbers of relatively small pollen grains (hence wind-pollinated plants may beallergens,

but seldom are animal-pollinated plants allergenic). Their stigmas may be large and

feathery to catch the pollen grains. Insects may visit them to collect pollen; in some

cases these are ineffective pollinators and exert little natural selection on the flowers,

but there are also examples of ambophilous flowers which are both wind and insect

pollinated .(Curtiz, 1968)

2. Water pollination (hydrophily)

Water-pollinated plants are aquatic and pollen is released into the water. Water

currents therefore act as a pollen vector in a similar way to wind currents. Their flowers

tend to be small and inconspicuous with lots of pollen grains and large, feathery stigmas

to catch the pollen. However, this is relatively uncommon (only 2% of pollination is

Hydrophily) and most aquatic plants are insect-pollinated, with flowers that emerge into

the air .(Curtiz, 1968)

3. Animal mediated pollination (zoidiophyly, zoidiogamy). Pollination is taking

place because there is the influence of animals as intermediaries. Pollination

usually occurs in plants that have characters as follows (Curtiz, 1968).

a. Having attractive colors

b. Produce something interesting or food animal

c. Pollen is often lumpy and sticky, so sticky to the bodies of animals that

visit flowers

d. Sometimes having a special shape, so the flowers can be visited by

certain animal species

Based on any class of animals that play a role in pollination, zoidiogamy can be

distinguished in (Dillon, 1964):

1. Insect-mediated pollination (entomophyly, entomogamy), for example

butterfly, bees, flies, etc.

2. Birds-mediated pollination (ornithophyly, ornitogamy)

3. Bats-mediated pollination (chiropterophyly, chiropterogamy)

4. Slugs-mediated pollination (malacophyly, malacogamy)

6. Fertilization

The pollen grains (microspores) are haploids cells, which are formed in the

anthers as a result of meiosis, from diploids microsphore mother cells

(microsporocytes). Each pollen grains is destined to grow into a gametophyte―in

this case, a male gametophyte. Such a development normally occurs only when

the mocrospore falls into the sugary secretion of a stigma of the same species,

although pollen grains can often be induced to germinate in artificial solution. The

male gametophyte, which is commonly called the pollen tube, now grows

downward through the tissue of the stigma and the style, deriving nourishment

and protection from these tissue. At maturity, when it penetrates an ovule and

approaches the egg cell, the male gametophyte consist of only three cells―or

rather consist of trinucleate syncytium. One of three nuclei is the tube nucleus,

which regulates the growth of the pollen tube; and the other two are sperm niclei.

One of these sperm nuclei unites with egg, forming the zygote, while the other

unites with both endosperm nuclei, forming a triploid endosperm cell. The process

called fertilization (Marsland,1964).

Fertilization occurs when a sperm nucleus leaves a pollen tube and fuses with an

egg nucleus. After fertilization, the zygotes multiplies by mitosis, and growing at

the expense of the surrounding endosperm tissue, it produces mass of diploid cells

that represents the embryo sporophyte (Marsland, 1964).

While the embrio is growing, many changes also occur in the several tissue, which lies in

direct contact with the embryo and provides it with organic food. The ovule taken as a

whole, become the seed and the ovule chamber also taken as a whole , enlarges and

becomes a fruit (Curtiz, 1968)

Conclution

Inflorescence should be distinguished from the branch that supports some of

flowers in axillary, but not easy to distinguish a compound interest from the

branch that has the flowers in axillary leaves. Inflorescence is one of two types

flowering in plants. Flower used to support produce fruits and seeds, trough the

pollination even and then fertilization.

REFERENCES

Curtis, Helena.1968. Biology. New York: Worth Publishers.

Dillon, Lawrence S.. 1964. The Science Of Life. New York: The Macmillan Company.

Marsland, Douglas. 1964. Principles Of Modern Biology. New York: Holt, Rinehart and Winston.

Sengupta, Saptacee. Pollination vs Fertilization. http//:www.buzzelus.

http://www.buzzle.com/articles/pollination-vs-fertilization.html. diakses 01 juni

2010.

Stein, Sammy. Pollination and fertilization in the gymnosperm.

Http://www.helium.com/items/1923324-pollination-and-fertilization-in-the-

gymnosperm. 01 Juni 2010

Tjitrosoepomo, Gembong. Morfologi Tumbuhan. Yogyakarta: Gadjah mada

university press. 2009.