Know and grow indigenous Spectacular, rewarding triton

by Graham Duncan, Kirstenbosch

From coastal roadsides of the south­ ern Cape to high altitude slopes of the Kwazulu-Natal Drakensberg, the mainly spring and summer-flower­ ing iridaceous contains about twenty-seven species of decidu­ ous, cormous . 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 ( 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 Tritonia crocata. Photo: Graham Duncan. 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

132 September 2006 Veld&Flora grown in Europe and England since possible, is necessary. Applications of phic species (such as T. watermeyen) the latter part of the eighteenth century organic fertilizer such as Kelpak 66 remain fully open irrespective ofweath­ and the colourful spring and early sum­ are beneficial to all tritonias at three­ er conditions, whereas those species mer-flowering hybrids commonly grown weekly intervals during the growing with regular or almost regular flowers today in gardens and window-boxes in period, or alternatively Neutrog Bounce (such as T. crocata) close slightly dur­ temperate regions, and in greenhouses Back pellets can be applied to the soil ing inclement weather. Owing to the in colder parts, are derived from mainly surface as a slow-release fertilizer. After ease with which some Tritonia species two species: the orange-flowered T. cro­ flowering, watering should be withheld hybridize when grown in close proxim­ cata and the pink-flowered T. squalida, as the leaves die back and seed forma­ ity (especially T. crocata, T. deusta and both of which emanate from the south­ tion takes place, and the corms should T. squalida), it is essential to isolate and ern Cape. Although easily cultivated, be allowed a completely dry summer or hand-pollinate specimens just prior to, the hybrids seldom outshine the true winter dormant rest, depending on the and during flowering, if pure seed is species in beauty, and with a sound species. required. Tritonias are hardy in mild knowledge of their cultivation require­ As tritonias have pronounced winter­ parts of the Northern Hemisphere and ments, a number of Tritonia species can or summer-growing cycles, it is essen­ in areas where winter temperatures be grown very successfully. tial to ascertain their correct growth do not remain below zero for pro­ cycle if they are to be cultivated suc­ longed periods, but in cold climates Cultivation cessfully. The winter-growing species they require the protection of the cool Ideal conditions for the successful cul­ require a dry summer rest while the greenhouse. In the wild, most winter­ tivation of Tritonia species include a summer-growers must he kept com­ growing tritonias flower in late spring sunny, well-ventilated aspect, a sharply­ pletely dry in winter. Some species are and early summer at a time when their drained growing medium, heavy drench­ able to tolerate a certain level of mois­ leaves are in an advanced state of des­ ing at regular intervals during the grow­ ture during their dormant period (such iccation, as temperatures rise and soil ing season, and maintenance of a dry as T. crocata and T. deusta) provided moisture rapidly diminishes. In order to period during dormancy. Although con­ that the soil medium is sufficiently. well ensure that the foliage of these species siderable variation exists in the depth drained, while others from arid habitats remains attractive and green through­ at which the corms of Tritonia species such as T. karooica, and T. watermeyeri out the flowering period in cultivation, occur in the wild, ranging from shallow are completely intolerant of moisture it is essential that the plants be kept to relatively deep-seated, under cultiva­ received at the wrong time of year and well watered by drenching them thor­ tion the corms of all species need only rot easily. All tritonias lend themselves oughly from late winter onwards, until be planted at roughly twice the height to cultivation in containers while only flowering has taken place. of the corm, or with about 2 cm of certain species are suited to general growing medium above the corm for the garden cultivation. The corms of arid Propagation smaller species like T. crocata and T. habitat members such as T. karoo­ All Tritonia species are easily propa­ watermeyeri, or about 4 cm above for ica and T. watermeyeri cannot survive gated by seed, and most can also be larger species like T. disticha and T. lin­ excessively moist conditions during increased by the separation of corm off­ eata. The corms of the winter-growers their winter growth period such as is sets and cormlets. In addition, cormels are planted in autumn (March to April) experienced in the southern suburbs are produced at the tips of horizontal, and for the summer-growers in spring of Cape Town, and have to be grown subterranean stolons in a few species. (August to September) in the Southern under cover in these areas. Large corm offsets are formed when two Hemisphere. Once planted they should The flowers of the strongly zygomor- or more shoots develop from the upper- be watered heavily and then not again until the leaf shoots appear, after which a heavy drench roughly once per week is suggested for most species. Watering RIGHT: One of the most spectacular species, of arid habitat species like T. karooica Tritonia squalida multiplies rapidly by and T. watermeyeri requires a measure corm offsets and has long-lasting flowers. of restraint and the frequency of water­ Note the distinctive translucent zones or ing for these should be delayed to per­ 'windows' along the tepal margins. Photo: Graham Duncan. haps once every ten days to two weeks, when the soil moisture has reached a much lower level. An ideal growing medium for most tritonias is one part river sand, one part loam and one part fmely sifted compost or finely milled bark. For arid habitat species the river The winter-growing sand component should be increased to two parts, and the loam component dis­ species require a dry pensed with entirely. The arid habitat summer rest while the tritonias require higher light intensity than most others for successful flower­ summer-growers must ing, but generally an aspect receiving be kept completely dry morning sun and afternoon shade, or bright light for as much of the day as in winter. lets and cormels usually take a further ABOVE LEFT: Tritonia deusta subsp. deusta year. For the winter-growers, seeds are occurs in colonies in the southem Cape coastal sown in autumn once temperatures districts from Caledon to Riversdale, and inland have cooled down markedly after the to Robertson and Montagu. It flowers in late hot summer, and for the summer-grow­ spring and early summer. ers, in spring, as temperatures rise. ABOVE RIGHT: A late-flowering species, the Fresh seeds germinate readily within easily grown Tritonia bakeri subsp. bakeri blooms from early to midsummer and has dis­ 2-4 weeks and care should be taken tinctive purple anthers. to sow thinly and ensure that a well­ RIGHT: Tritonia crocata is one of the most ventilated environment is maintained obliging species in cultivation, highly recom­ in order to reduce the incidence of mended for massed display in rock garden damping-off fungi. Seeds can be sown pockets, spring borders and deep containers. in deep seed trays or seedbeds in the Photos: Graham Duncan. same medium recommended for mature corms. The deeper the seed trays or What does that mean? beds, the faster the young corms will develop and reach flowering stage. The axillary bud bud arising from a corm at the seeds are covered with 3-4 mm of sow­ juncture formed by a leaf or bract and corm ing medium and should be sown in an corm compressed, swollen subterranean area receiving high light intensity, or stem which is vertically orientated, renewed full morning sun and afternoon shade. annually and covered by dry leaf bases They should be kept moist by watering cormel small corm that develops at the tip thoroughly with a fine rose about twice of a stolon or three times per week, depending on cormlets small corms that develop in a ring weather conditions. Seedlings of easily around the base of a mother corm cultivated species like T. crocata and T. offset a short shoot that arises from an axil­ squalida will usually flower for the first lary bud near the base of a stem and gives most axillary buds on the mother corm, time during their second season, while rise to a daughter at its apex. while smaller cormlets develop from larger species like T. lineata and those perianth the sepals and petals together, par­ lower axillary buds around the base from arid habitats such as T. karoa­ ticularly when they are similar of mother corms. They develop during ica and T. watermeyeri will usually rhizome specialized underground stem that the growing period and mature towards flower in their third year, under ideal grows horizontally, producing roots and foli­ the end of the flowering season. They conditions. age at right angles to the rhizome can be separated at any time during stolon thin, elongated stem trailing over the corresponding dormant period and Pests and diseases or just under the soil surface, producing a should preferably be re-planted immedi­ Compared with other southern African cormel at its tip ately into dry soil, as the corms are fre­ irids, tritonias are moderately suscep­ tepal sepal or petal, when no distinction is quently subject to mealy bug infestation tible to pests and diseases. The corms made between them if stored loose in packets or trays for and leaf bases are subject to the univer­ zygomorphic irregular, and able to be bisect­ long periods. Corm offsets often flower sal mealy bug scourge, against which ed into identical halves in one plane only during their second year while corm- a preventative treatment of a mineral

134 September 2006 Veld&Flora oil drench (e.g. Oleum) can be applied the season, from early to midsummer ter-growing plant and occurs in large in early autumn for the winter-grow­ and has distinctive narrow, erect cylin­ colonies in coastal parts of the southern ers, and in early spring for the sum­ drical leaves. It performs well in deep Cape stretching from Swellendam to mer-growers. Developing flower buds containers and although the corms are George and Humansdorp. It produces may at times become heavily infested long-lived, they are rather slow to mul­ an attractive fan of lance-shaped leaves with thrips, especially in the summer­ tiply. It is easily raised from seeds sown and flower colour varies from shades growing species, resulting in deformed in autumn, the seedlings usually reach­ of bright fiery orange to deep orange­ flowers. In highly susceptible areas the ing flowering stage at the end of their red or pinkish-orange. The three lower flower buds should be sprayed pre­ third year, under ideal conditions. tepals have a narrow yellow or dark red ventatively with Bio Kill garden spray central stripe in the throat, and all the as soon as they emerge, well before the Tritonia crocata (kalkoentjie) is prob­ tepals have attractive narrow translu­ thrips have had a chance to invade. ably the best-known member in cultiva­ cent zones or 'windows' on the margins. Flower buds and leaves are sometimes tion and together with T. squalida was It is one of the most easily cultivated subject to attack by aphids, and red one of the species used in the creation tritonias, reaching up to 450 mm high, spider mites are prevalent on the foliage of the brightly coloured hybrids widely providing a brilliant, reliable display of the broader-leafed species as tem­ grown in temperate gardens throughout from mid-spring to early summer. It peratures rise in spring and throughout the world today. It is a variable, win- is suited to rock garden pockets and summer, resulting in leaf desiccation and a silvery-bronze sheen, for which a full cover spray with Oleum is recom­ mended. The corms of Tritonia species are taken by porcupines and mole rats. Jelly-like scatter crystals known in the trade as 'Get Off My Garden' may be effective in deterring porcupines, while molerats can be temporarily beaten by planting corms in sunken wire baskets protected on all sides. The leaves of certain winter-growing species especially T. crocata, T. deus­ ta and T. squalida are susceptible to attack by unsightly rust fungi in winter, and it is essential that they be grown in well ventilated positions receiving as much direct sun or bright light as pos­ sible. In severe infestations rust fungi can be controlled with mancozeb (e.g. Dithane M45). All Tritonia species are subject to fungal infection by Botrytis which causes reddish-brown lesions on the corms, and can be controlled by dusting corms with captab (e.g. Kaptan) prior to planting. Tritonia seedlings are susceptible to damping-off by Pythium fungi which is prevalent in poorly ven­ tilated conditions and when seeds have been sown too thickly. The seeds can be dusted with Kaptan prior to sowing. ABOVE: Tritonia disticha subsp. rubrolucens, flowering on Mt. Thomas in the Eastern Cape, is a summer-growing, high altitude tritonia. Photo: Cameron McMaster. Ten of the best RIGHT: Tritonia karooica has attractive bluish­ Tritonia bakeri is an elegant, large­ grey leaves and requires high light intensity flowered species growing up to 800 mm and a sharply drained growing medium for high with pure white, creamy-yellow successful flowering. Photo: Graham Duncan. or mauvish-pink blooms with striking violet anthers and a very long perianth tube. The subspecies bakeri (see illus­ tration) has white or creamy-yellow flowers while those of the subspecies lilacina are smaller and pale mauvish­ pink. T. bakeri is a winter-grower from the Little Karoo and Langkloof, and also occurs in the southern Cape from George to Riversdale. It flowers late in duces an attractive fan of lance-shaped leaves, grows to 450 mm high in culti­ vation and multiplies rapidly by corm offsets. Flowering takes place from late spring to early summer and it is well suited to rock garden pockets and deep containers. It readily hybridizes with T. crocata and T. squalida and flowers must be isolated and hand-pollinated in order to obtain pure seed.

Tritonia disticha is a summer-grower and has a fairly wide distribution extend­ ing from the south-eastern parts of the Eastern Cape to KwaZulu-Natal, the north-eastern Free State, Mpumalanga and Swaziland. It has long, narrowly lance-shaped leaves and a many-flow­ ered spike up to I m high consisting of widely funnel-shaped pink, red or orangy-red flowers with a small yel­ low marking outlined in red on the lower tepals. The subspecies disticha occurs at lower altitude and has longer bracts than those of subsp. rubrolucens which occurs at higher altitude (and is illustrated on p. 135). This species has a long flowering period from early summer to early autumn and is easily maintained in cultivation provided the corms are kept completely dry over the winter dormant period, and that mealy bugs are judiciously controlled.

Tritonia karooica is widely distributed throughout the western and northern parts of the Great Karoo and is a win­ ter-growing plant up to 200 mm high that flowers early in the season, from early to mid-spring. Its dark bluish-grey leaves are borne in an attractive fan, and the funnel-shaped flowers occur in shades of brownish-yellow, cream, burnt orange or salmon, with promi­ nent darker veins and bright yellow ABOVE: The curious wavy-margined grey leaves and long-lasting blooms of Tritonia watermeyeri make it one markings on the lower three tepals. The of the most rewarding tritonias to grow in containers. Note the three prominent yellow protrusions on the lower tepals, whose function is thought to reduce the space in the throat of the perianth, thus ensuring that tepal tips become strongly re-curved the back of avisiting insect will brush against the anthers and stigmas, facilitating pollination. with age and the flowers emit a pleas­ Photo: Graham Duncan. ant sweet fragrance in the evening. The plants are very sensitive to over-water­ ing and must have very bright light and sharply drained soil in order to flower deep containers, and multiplies rapidly tepals. It occurs in the southern Cape successfully. Corm offsets are slow to by corm offsets. It readily hybridizes from Caledon to Riversdale and inland develop and it is best propagated from with T. deusta and T. squalida and the to Robertson and Montagu. It is eas­ seeds, that flower in their third season. flowers must be isolated and hand-pol­ ily confused with T. crocata, differing linated in order to obtain pure seed. mainly in the absence of translucent Tritonia laxijolia is a summer-grower zones or 'windows' on the margins of with a wide distribution extending from Tritonia deusta (kalkoentjie) is a vari­ the tepals, and in having a prominent the eastern parts of the Eastern Cape able, winter-growing species with large yellow, star-shaped base within the to the north-eastern parts of the Great orange-salmon to bright reddish-orange perianth tube. The subspecies deusta Karoo, up to the Central African coun­ flowers, with or without a prominent has redddish-black markings on the tries of Malawi, Zambia and Tanzania. dark reddish-black marking or cen­ outer tepals, while in the subspecies It grows to 600 mm high and has a tral stripe in the throat of the outer miniata there are no markings. It pro- long flowering period extending from

136 September 2006 Veld&Flora early to late autumn in southern Africa, herbarium specimens, the flower colour prominent bright yellow, narrow peg­ to midwinter in Central Africa. The fades to a dirty brownish-mauve colour, like protrusions extend upwards from plants have narrow linear leaves and hence the species name given by an the lower tepals. It performs extremely bear graceful lax spikes of six to fifteen unsuspecting botanist in the late eight­ well in cultivation provided the corms bright salmon-pink to pale brick-red eenth century, who evidently had never are kept completely dry over the sum­ flowers, each of the three lower tepals seen it in the living state. Endemic to a mer dormant period, and it is most con­ having a bright yellow peg-like protru­ small area of the southern Cape from veniently grown as a container subject sion that extends upwards. This species Albertinia to Stilbaai, it is a winter­ in a sharply drained mix of coarse river prefers a lightly shaded position and grower and closely resembles T. crocata sand and silica sand, with the addition is most suitably grown as a container in flower and leaf shape, differing main­ of a little finely sifted compost. Plant subject. The corms must be kept dry ly in the distinctive deep mauvish-pink height varies from 100-300 mm and it over the winter dormant season and a to pale pink colouring of the flowers, flowers from early to mid-spring. close watch should be kept for mealy with prominent deeper pink veins in bug infestation, to which it is particu­ the tepals, and in the absence of a nar­ Sources of supply larly susceptible. row, yellow central stripe in the throat Seeds of several Tritonia species are in the three lower tepals. An especially listed from time to time in the annual Tritonia lineata (bergkatjietee) is a attractive feature of the flowers is the Kirstenbosch seed catalogue, issued summer-grower and is a very common wide translucent zones or 'windows' on free to South African members of the species in the eastern and south-east­ the margins of the tepals. Growing up Botanical Society of South Africa, or ern parts of the Eastern Cape, and is to 450 mm high, it is one of the most for sale when stocks are large enough. also widely distributed in the eastern desirable and easily cultivated tritonias Seeds of certain species, including T. summer rainfall regions of South Africa and multiplies rapidly by corm offsets. bakeri, T. watermeyeri and T. karooica in KwaZulu-Natal, eastern Free State, It flowers in late spring and is suited to are not yet easily obtainable. Tritonia Mpumalanga and Lesotho. It flowers cultivation in deep containers and rock corms are seldom available from special­ from early spring to midsummer, and garden pockets in temperate climates. ist nurseries but can be purchased is dormant during the winter months. It readily hybridizes with T. crocata and periodically at the Botanical Society's It has cream or yellow, funnel-shaped T. deusta and the flowers need to be annual Garden Fair and at the Centre flowers distinctly marked with brown­ isolated and hand-pollinated in order to for Home Gardening at Kirstenbosch. ~ ish lines, narrowly lance-shaped leaves, obtain pure seed. and grows up to 850 mm high. The vari­ ety lineata grows to well above 300 mm Tritonia watermeyeri is a winter­ high whereas the variety parvifolia has growing dwarf species with a very lim­ Further reading shorter, narrower leaves up to 300 mm ited distribution in the Little Karoo east De Vos, M. P 1999. Tritonia. In: De Vos, M. high. This species performs very well in of Montagu. Its distinctive grey leaves P and Goldblatt, P, Flora of southern Africa cultivation, multiplying rapidly by corm are as interesting as the flowers and 7(2), 89-128. offsets and by seed, and is most suit­ have strongly wavy margins that are Du Plessis, N. M. and Duncan, G. D. 1989. ably grown in rock garden pockets, her­ sometimes spirally twisted. The showy Bulbous plants of southern Africa, pp. 132­ baceous borders or deep containers. spike is borne on a wiry dark brown 134. Tafelberg, Cape Town. peduncle and bears 3-7 burnt orange, Jeppe, B. J. and Duncan, G. D. 1989. Spring Tritonia securigera (tritonia, slightly fragrant flowers with a red­ and winter flowering bulbs of the Cape, pp. kalkoentjie) is a very variable, winter­ edged yellow zone in the throat. Three 62-65. Oxford University Press, Cape Town. growing species and occurs in the Little Karoo, the eastern parts of the Great Karoo and in the southern Cape from The author Mossel Bay to Humansdorp. lt has Graham Duncan, horticulturist and 'bulb lance-shaped, somewhat rigid foliage expert' from Kirstenbosch, graduated cum and attractive sprays of reddish-orange laude from the University of KwaZulu-Natal blooms with yellow throats, each of the in April last year with an M.Sc. in Botany. three lower tepals with a prominent The title of his dissertation was 'Character peg-like protrusion arising from the variation and a cladistic analysis of the base. It flowers from late spring to early genus Lachenalia.' He is the author of summer and the plants can grow up to numerous books and articles and also 350 mm high under ideal conditions. a past winner of the BotSoc's Schelpe The corms multiply rapidly by offset Award for the best horticultural article in formation and an abundance of seed Veld &Flora. is set in cultivation following hand pol­ lination. lt is well suited to rock garden pockets and deep containers.

Tritonia squalida (Mosselbaai­ kalkoentjie, kalkoentjie) has been sad­ dled with a grossly inappropriate spe­ cific name as it ranks as one of the most beautiful of all the tritonias. In The author, Graham Duncan.

September 2006 Veld&Flora 137