Know and grow indigenous bulbs
Spectacular, rewarding triton
Tritonia crocata. Photo: Graham Duncan.
132 September 2006 Veld&Flora
by Graham Duncan, Kirstenbosch
From coastal roadsides of the south
ern Cape to high altitude slopes of
the Kwazulu-Natal Drakensberg, themainly spring and summer-flower
ing iridaceous genus Tritonia contains
about twenty-seven species of decidu
ous, cormous plants. They are encoun
tered in all provinces of South Africa as
well as in Lesotho and Swaziland, and
their distribution extends northwards
almost to the equator in Tanzania in
Central East Africa. Tritonia was stud
ied in detail by Dr Miriam P. de Vos in
the early 1980s and her excellent final
account of the genus appeared in the
Flora of southern Africa, in 1999. The
genus is concentrated in the south
ern Cape and most of the species are
adapted to winter rainfall conditions,
flowering taking place mainly in spring
and early summer. The summer-grow
ers flower mainly from midsummer to
autumn. They occur in greatly differing
habitats, from arid rocky slopes of the
southern Richtersveld to high rainfall
parts of the northern Drakensberg.
Flower shape varies from regular to
strongly zygomorphic (see glossary on
p. 134), with flower colour predominat
ing in shades of orange.
Two species (Tritonia crocata and
T. squalida) are particularly showy in
having curious translucent zones or
'windows' along the margins of their
tepals. In a number of others, promi
nent yellow, erect, peg-like protuber
ances emerge from the lower tepals
and are thought to function in reducing
the space in the throat of the perianth,
thus ensuring that the back of a visiting
insect will brush against the anthers
and stigma and ensure pollination, as
in T. watermeyeri. The attractive fan
like foliage varies from bright green with
flat margins to grey and spirally twisted
with heavily wavy margins. The genus
Tritonia was brought into being by the
English botanist J. B. Ker-Gawler in
1802, who named it for the Latin word
triton, a weathervane, for the vari
able orientation of the stamens in some
species.
Tritonias or 'kalkoentjies' as some
species are locally known, have been
grown in Europe and England sincethe latter part of the eighteenth centuryand the colourful spring and early summer-flowering hybrids commonly growntoday in gardens and window-boxes intemperate regions, and in greenhousesin colder parts, are derived from mainlytwo species: the orange-flowered T. crocata and the pink-flowered T. squalida,both of which emanate from the southern Cape. Although easily cultivated,the hybrids seldom outshine the truespecies in beauty, and with a soundknowledge of their cultivation requirements, a number of Tritonia species canbe grown very successfully.
CultivationIdeal conditions for the successful cultivation of Tritonia species include asunny, well-ventilated aspect, a sharplydrained growing medium, heavy drenching at regular intervals during the growing season, and maintenance of a dryperiod during dormancy. Although considerable variation exists in the depthat which the corms of Tritonia speciesoccur in the wild, ranging from shallowto relatively deep-seated, under cultivation the corms of all species need onlybe planted at roughly twice the heightof the corm, or with about 2 cm ofgrowing medium above the corm for thesmaller species like T. crocata and T.watermeyeri, or about 4 cm above forlarger species like T. disticha and T. lineata. The corms of the winter-growersare planted in autumn (March to April)and for the summer-growers in spring(August to September) in the SouthernHemisphere. Once planted they shouldbe watered heavily and then not againuntil the leaf shoots appear, after whicha heavy drench roughly once per weekis suggested for most species. Wateringof arid habitat species like T. karooicaand T. watermeyeri requires a measureof restraint and the frequency of watering for these should be delayed to perhaps once every ten days to two weeks,when the soil moisture has reacheda much lower level. An ideal growingmedium for most tritonias is one partriver sand, one part loam and one partfmely sifted compost or finely milledbark. For arid habitat species the riversand component should be increased totwo parts, and the loam component dispensed with entirely. The arid habitattritonias require higher light intensitythan most others for successful flowering, but generally an aspect receivingmorning sun and afternoon shade, orbright light for as much of the day as
possible, is necessary. Applications oforganic fertilizer such as Kelpak 66are beneficial to all tritonias at threeweekly intervals during the growingperiod, or alternatively Neutrog BounceBack pellets can be applied to the soilsurface as a slow-release fertilizer. Afterflowering, watering should be withheldas the leaves die back and seed formation takes place, and the corms shouldbe allowed a completely dry summer orwinter dormant rest, depending on thespecies.
As tritonias have pronounced winteror summer-growing cycles, it is essential to ascertain their correct growthcycle if they are to be cultivated successfully. The winter-growing speciesrequire a dry summer rest while thesummer-growers must he kept completely dry in winter. Some species areable to tolerate a certain level of moisture during their dormant period (suchas T. crocata and T. deusta) providedthat the soil medium is sufficiently. welldrained, while others from arid habitatssuch as T. karooica, and T. watermeyeriare completely intolerant of moisturereceived at the wrong time of year androt easily. All tritonias lend themselvesto cultivation in containers while onlycertain species are suited to generalgarden cultivation. The corms of aridhabitat members such as T. karooica and T. watermeyeri cannot surviveexcessively moist conditions duringtheir winter growth period such as isexperienced in the southern suburbsof Cape Town, and have to be grownunder cover in these areas.
The flowers of the strongly zygomor-
RIGHT: One of the most spectacular species,Tritonia squalida multiplies rapidly bycorm offsets and has long-lasting flowers.Note the distinctive translucent zones or'windows' along the tepal margins.Photo: Graham Duncan.
The winter-growingspecies require a drysummer rest while thesummer-growers mustbe kept completely dryin winter.
phic species (such as T. watermeyen)remain fully open irrespective ofweather conditions, whereas those specieswith regular or almost regular flowers(such as T. crocata) close slightly during inclement weather. Owing to theease with which some Tritonia specieshybridize when grown in close proximity (especially T. crocata, T. deusta and
T. squalida), it is essential to isolate andhand-pollinate specimens just prior to,and during flowering, if pure seed isrequired. Tritonias are hardy in mildparts of the Northern Hemisphere andin areas where winter temperaturesdo not remain below zero for prolonged periods, but in cold climatesthey require the protection of the coolgreenhouse. In the wild, most wintergrowing tritonias flower in late springand early summer at a time when theirleaves are in an advanced state of desiccation, as temperatures rise and soilmoisture rapidly diminishes. In order toensure that the foliage of these speciesremains attractive and green throughout the flowering period in cultivation,it is essential that the plants be keptwell watered by drenching them thoroughly from late winter onwards, untilflowering has taken place.
PropagationAll Tritonia species are easily propagated by seed, and most can also beincreased by the separation of corm offsets and cormlets. In addition, cormelsare produced at the tips of horizontal,subterranean stolons in a few species.Large corm offsets are formed when twoor more shoots develop from the upper-
ABOVE LEFT: Tritonia deusta subsp. deustaoccurs in colonies in the southem Cape coastaldistricts from Caledon to Riversdale, and inlandto Robertson and Montagu. It flowers in latespring and early summer.
ABOVE RIGHT: A late-flowering species, theeasily grown Tritonia bakeri subsp. bakeriblooms from early to midsummer and has distinctive purple anthers.
RIGHT: Tritonia crocata is one of the mostobliging species in cultivation, highly recommended for massed display in rock gardenpockets, spring borders and deep containers.Photos: Graham Duncan.
What does that mean?
axillary bud bud arising from a corm at thejuncture formed by a leaf or bract and cormcorm compressed, swollen subterraneanstem which is vertically orientated, renewedannually and covered by dry leaf basescormel small corm that develops at the tipof a stoloncormlets small corms that develop in a ringaround the base of amother cormoffset a short shoot that arises from an axillary bud near the base of a stem and givesrise to adaughter plant at its apex.perianth the sepals and petals together, particularly when they are similarrhizome specialized underground stem thatgrows horizontally, producing roots and foliage at right angles to the rhizomestolon thin, elongated stem trailing overor just under the soil surface, producing acormel at its tiptepal sepal or petal, when no distinction ismade between themzygomorphic irregular, and able to be bisected into identical halves in one plane only
134 September 2006 Veld&Flora
most axillary buds on the mother corm,
while smaller cormlets develop fromlower axillary buds around the baseof mother corms. They develop during
the growing period and mature towardsthe end of the flowering season. Theycan be separated at any time duringthe corresponding dormant period and
should preferably be re-planted immediately into dry soil, as the corms are frequently subject to mealy bug infestationif stored loose in packets or trays forlong periods. Corm offsets often flowerduring their second year while corm-
lets and cormels usually take a furtheryear. For the winter-growers, seeds are
sown in autumn once temperatureshave cooled down markedly after thehot summer, and for the summer-growers, in spring, as temperatures rise.Fresh seeds germinate readily within2-4 weeks and care should be taken
to sow thinly and ensure that a wellventilated environment is maintainedin order to reduce the incidence ofdamping-off fungi. Seeds can be sown
in deep seed trays or seedbeds in thesame medium recommended for maturecorms. The deeper the seed trays orbeds, the faster the young corms willdevelop and reach flowering stage. The
seeds are covered with 3-4 mm of sowing medium and should be sown in anarea receiving high light intensity, orfull morning sun and afternoon shade.
They should be kept moist by wateringthoroughly with a fine rose about twiceor three times per week, depending onweather conditions. Seedlings of easilycultivated species like T. crocata and T.
squalida will usually flower for the firsttime during their second season, whilelarger species like T. lineata and thosefrom arid habitats such as T. karoaica and T. watermeyeri will usuallyflower in their third year, under idealconditions.
Pests and diseases
Compared with other southern Africanirids, tritonias are moderately susceptible to pests and diseases. The cormsand leaf bases are subject to the universal mealy bug scourge, against whicha preventative treatment of a mineral
oil drench (e.g. Oleum) can be appliedin early autumn for the winter-grow
ers, and in early spring for the summer-growers. Developing flower budsmay at times become heavily infestedwith thrips, especially in the summer
growing species, resulting in deformedflowers. In highly susceptible areas theflower buds should be sprayed pre
ventatively with Bio Kill garden sprayas soon as they emerge, well before thethrips have had a chance to invade.Flower buds and leaves are sometimessubject to attack by aphids, and red
spider mites are prevalent on the foliageof the broader-leafed species as temperatures rise in spring and throughoutsummer, resulting in leaf desiccation
and a silvery-bronze sheen, for whicha full cover spray with Oleum is recommended. The corms of Tritonia species
are taken by porcupines and mole rats.Jelly-like scatter crystals known in thetrade as 'Get Off My Garden' may be
effective in deterring porcupines, whilemolerats can be temporarily beaten by
planting corms in sunken wire basketsprotected on all sides.
The leaves of certain winter-growingspecies especially T. crocata, T. deus
ta and T. squalida are susceptible toattack by unsightly rust fungi in winter,and it is essential that they be grownin well ventilated positions receiving asmuch direct sun or bright light as possible. In severe infestations rust fungi
can be controlled with mancozeb (e.g.Dithane M45). All Tritonia species aresubject to fungal infection by Botrytis
which causes reddish-brown lesions
on the corms, and can be controlled bydusting corms with captab (e.g. Kaptan)prior to planting. Tritonia seedlings aresusceptible to damping-off by Pythium
fungi which is prevalent in poorly ven
tilated conditions and when seeds havebeen sown too thickly. The seeds can bedusted with Kaptan prior to sowing.
Ten of the bestTritonia bakeri is an elegant, largeflowered species growing up to 800 mmhigh with pure white, creamy-yellowor mauvish-pink blooms with striking
violet anthers and a very long perianthtube. The subspecies bakeri (see illustration) has white or creamy-yellow
flowers while those of the subspecieslilacina are smaller and pale mauvishpink. T. bakeri is a winter-grower from
the Little Karoo and Langkloof, andalso occurs in the southern Cape fromGeorge to Riversdale. It flowers late in
the season, from early to midsummerand has distinctive narrow, erect cylin
drical leaves. It performs well in deepcontainers and although the corms arelong-lived, they are rather slow to mul
tiply. It is easily raised from seeds sownin autumn, the seedlings usually reach
ing flowering stage at the end of theirthird year, under ideal conditions.
Tritonia crocata (kalkoentjie) is probably the best-known member in cultivation and together with T. squalida wasone of the species used in the creation
of the brightly coloured hybrids widelygrown in temperate gardens throughoutthe world today. It is a variable, win-
ABOVE: Tritonia disticha subsp. rubrolucens,flowering on Mt. Thomas in the Eastern Cape, isa summer-growing, high altitude tritonia.Photo: Cameron McMaster.
RIGHT: Tritonia karooica has attractive bluishgrey leaves and requires high light intensityand a sharply drained growing medium forsuccessful flowering. Photo: Graham Duncan.
ter-growing plant and occurs in largecolonies in coastal parts of the southernCape stretching from Swellendam toGeorge and Humansdorp. It produces
an attractive fan of lance-shaped leavesand flower colour varies from shadesof bright fiery orange to deep orange
red or pinkish-orange. The three lower
tepals have a narrow yellow or dark redcentral stripe in the throat, and all thetepals have attractive narrow translu
cent zones or 'windows' on the margins.It is one of the most easily cultivatedtritonias, reaching up to 450 mm high,providing a brilliant, reliable displayfrom mid-spring to early summer. It
is suited to rock garden pockets and
ABOVE: The curious wavy-margined grey leaves and long-lasting blooms of Tritonia watermeyeri make it oneof the most rewarding tritonias to grow in containers. Note the three prominent yellow protrusions on thelower tepals, whose function is thought to reduce the space in the throat of the perianth, thus ensuring thatthe back of avisiting insect will brush against the anthers and stigmas, facilitating pollination.Photo: Graham Duncan.
deep containers, and multiplies rapidlyby corm offsets. It readily hybridizes
with T. deusta and T. squalida and theflowers must be isolated and hand-pollinated in order to obtain pure seed.
Tritonia deusta (kalkoentjie) is a vari
able, winter-growing species with largeorange-salmon to bright reddish-orangeflowers, with or without a prominentdark reddish-black marking or central stripe in the throat of the outer
136 September 2006 Veld&Flora
tepals. It occurs in the southern Capefrom Caledon to Riversdale and inlandto Robertson and Montagu. It is eas
ily confused with T. crocata, differingmainly in the absence of translucentzones or 'windows' on the margins ofthe tepals, and in having a prominentyellow, star-shaped base within the
perianth tube. The subspecies deustahas redddish-black markings on the
outer tepals, while in the subspeciesminiata there are no markings. It pro-
duces an attractive fan of lance-shapedleaves, grows to 450 mm high in cultivation and multiplies rapidly by corm
offsets. Flowering takes place from latespring to early summer and it is wellsuited to rock garden pockets and deepcontainers. It readily hybridizes with
T. crocata and T. squalida and flowersmust be isolated and hand-pollinated inorder to obtain pure seed.
Tritonia disticha is a summer-grower
and has a fairly wide distribution extending from the south-eastern parts of theEastern Cape to KwaZulu-Natal, the
north-eastern Free State, Mpumalangaand Swaziland. It has long, narrowlylance-shaped leaves and a many-flow
ered spike up to I m high consistingof widely funnel-shaped pink, red or
orangy-red flowers with a small yellow marking outlined in red on thelower tepals. The subspecies distichaoccurs at lower altitude and has longer
bracts than those of subsp. rubrolucenswhich occurs at higher altitude (andis illustrated on p. 135). This specieshas a long flowering period from earlysummer to early autumn and is easilymaintained in cultivation provided thecorms are kept completely dry over the
winter dormant period, and that mealybugs are judiciously controlled.
Tritonia karooica is widely distributedthroughout the western and northernparts of the Great Karoo and is a win
ter-growing plant up to 200 mm high
that flowers early in the season, fromearly to mid-spring. Its dark bluish-greyleaves are borne in an attractive fan,and the funnel-shaped flowers occurin shades of brownish-yellow, cream,burnt orange or salmon, with promi
nent darker veins and bright yellowmarkings on the lower three tepals. Thetepal tips become strongly re-curvedwith age and the flowers emit a pleasant sweet fragrance in the evening. Theplants are very sensitive to over-watering and must have very bright light and
sharply drained soil in order to flowersuccessfully. Corm offsets are slow todevelop and it is best propagated fromseeds, that flower in their third season.
Tritonia laxijolia is a summer-growerwith a wide distribution extending from
the eastern parts of the Eastern Capeto the north-eastern parts of the GreatKaroo, up to the Central African countries of Malawi, Zambia and Tanzania.
It grows to 600 mm high and has along flowering period extending from
early to late autumn in southern Africa,to midwinter in Central Africa. The
plants have narrow linear leaves andbear graceful lax spikes of six to fifteenbright salmon-pink to pale brick-redflowers, each of the three lower tepalshaving a bright yellow peg-like protru
sion that extends upwards. This speciesprefers a lightly shaded position andis most suitably grown as a containersubject. The corms must be kept dry
over the winter dormant season and aclose watch should be kept for mealybug infestation, to which it is particularly susceptible.
Tritonia lineata (bergkatjietee) is asummer-grower and is a very commonspecies in the eastern and south-eastern parts of the Eastern Cape, and is
also widely distributed in the easternsummer rainfall regions of South Africain KwaZulu-Natal, eastern Free State,Mpumalanga and Lesotho. It flowers
from early spring to midsummer, andis dormant during the winter months.It has cream or yellow, funnel-shapedflowers distinctly marked with brownish lines, narrowly lance-shaped leaves,and grows up to 850 mm high. The variety lineata grows to well above 300 mm
high whereas the variety parvifolia hasshorter, narrower leaves up to 300 mmhigh. This species performs very well incultivation, multiplying rapidly by cormoffsets and by seed, and is most suitably grown in rock garden pockets, her
baceous borders or deep containers.
Tritonia securigera (tritonia,kalkoentjie) is a very variable, wintergrowing species and occurs in the Little
Karoo, the eastern parts of the GreatKaroo and in the southern Cape fromMossel Bay to Humansdorp. lt haslance-shaped, somewhat rigid foliageand attractive sprays of reddish-orange
blooms with yellow throats, each of thethree lower tepals with a prominentpeg-like protrusion arising from thebase. It flowers from late spring to early
summer and the plants can grow up to350 mm high under ideal conditions.The corms multiply rapidly by offset
formation and an abundance of seedis set in cultivation following hand pollination. lt is well suited to rock garden
pockets and deep containers.
Tritonia squalida (Mosselbaaikalkoentjie, kalkoentjie) has been saddled with a grossly inappropriate specific name as it ranks as one of the
most beautiful of all the tritonias. In
herbarium specimens, the flower colourfades to a dirty brownish-mauve colour,hence the species name given by anunsuspecting botanist in the late eight
eenth century, who evidently had neverseen it in the living state. Endemic to asmall area of the southern Cape fromAlbertinia to Stilbaai, it is a wintergrower and closely resembles T. crocatain flower and leaf shape, differing mainly in the distinctive deep mauvish-pinkto pale pink colouring of the flowers,with prominent deeper pink veins inthe tepals, and in the absence of a nar
row, yellow central stripe in the throatin the three lower tepals. An especiallyattractive feature of the flowers is thewide translucent zones or 'windows' on
the margins of the tepals. Growing upto 450 mm high, it is one of the mostdesirable and easily cultivated tritoniasand multiplies rapidly by corm offsets.It flowers in late spring and is suited to
cultivation in deep containers and rockgarden pockets in temperate climates.It readily hybridizes with T. crocata andT. deusta and the flowers need to beisolated and hand-pollinated in order to
obtain pure seed.
Tritonia watermeyeri is a wintergrowing dwarf species with a very limited distribution in the Little Karoo eastof Montagu. Its distinctive grey leavesare as interesting as the flowers and
have strongly wavy margins that aresometimes spirally twisted. The showy
spike is borne on a wiry dark brownpeduncle and bears 3-7 burnt orange,slightly fragrant flowers with a red
edged yellow zone in the throat. Three
The authorGraham Duncan, horticulturist and 'bulbexpert' from Kirstenbosch, graduated cumlaude from the University of KwaZulu-Natalin April last year with an M.Sc. in Botany.The title of his dissertation was 'Charactervariation and a cladistic analysis of thegenus Lachenalia.' He is the author ofnumerous books and articles and alsoa past winner of the BotSoc's SchelpeAward for the best horticultural article inVeld &Flora.
prominent bright yellow, narrow peglike protrusions extend upwards from
the lower tepals. It performs extremelywell in cultivation provided the cormsare kept completely dry over the summer dormant period, and it is most conveniently grown as a container subject
in a sharply drained mix of coarse riversand and silica sand, with the addition
of a little finely sifted compost. Plantheight varies from 100-300 mm and itflowers from early to mid-spring.
Sources of supply
Seeds of several Tritonia species arelisted from time to time in the annualKirstenbosch seed catalogue, issuedfree to South African members of theBotanical Society of South Africa, or
for sale when stocks are large enough.Seeds of certain species, including T.bakeri, T. watermeyeri and T. karooicaare not yet easily obtainable. Tritoniacorms are seldom available from specialist bulb nurseries but can be purchasedperiodically at the Botanical Society'sannual Garden Fair and at the Centrefor Home Gardening at Kirstenbosch.~
Further readingDe Vos, M. P 1999. Tritonia. In: De Vos, M.P and Goldblatt, P, Flora of southern Africa7(2), 89-128.Du Plessis, N. M. and Duncan, G. D. 1989.Bulbous plants of southern Africa, pp. 132134. Tafelberg, Cape Town.Jeppe, B. J. and Duncan, G. D. 1989. Springand winter flowering bulbs of the Cape, pp.62-65. Oxford University Press, Cape Town.
The author, Graham Duncan.
September 2006 Veld&Flora 137