THREE SPECTACULAR SPECIES FROM SOUTH AFRICA’S GRASSLANDS AND SAVANAH..
SUMMARY.
South Africa is home to several rare and spectacular Crinums.
The different species inhabit arid savanah, coastal grassland and seasonal marshes and watercourses. Some are also found in the climatically severe interior where they occur in short grassland.
Most Crinums flowers from spring to mid-summer, generally blooming within the first few weeks after the onset of the main summer rains.
Crinums grow well in large containers and also thrive in well drained situations in gardens.
Penrock Seeds and Plants will feature several newsletters about Crinums. This one, the first in the series, concerns three spectacular species, Crinum acaule, Crinum delagoense and Crinum foetidum. An account is given of plants in their natural habitat as well as the plants’ requirements in cultivation.
CRINUM ACAULE, CRINUM DELAGOENSE AND CRINUM FOETIDUM.
THREE SPECTACULAR SPECIES FROM SOUTH AFRICA’S GRASSLANDS AND SAVANAH.
Crinum acaule is found in northern Natal mostly on the Maputaland coastal plain. The plants grow either singly or in clumps in sandy soil. The main habitat is gently undulating coastal grassland. Some of the plants are conserved in the greater St. Lucia Wetland Park. Most of the C. acaule habitat has however undergone extensive aforestation with exotics and also degradation in some densely settled areas.
This species is one of the earliest Crinums to flower in South Africa. The flowering season extends from late September until late November. The peak flowering period is usually the first half of October. The bulbs do not require rain to initiate flowering. Spring rains in October do however result in mass flowering, particularly if the grass is short or has been burnt during the winter months.
Crinum acaule in flower in short coastal grassland west of Lake St. Lucia. This photograph was taken on 18 October 2003. October is usually the peak flowering month for this species.
C. acaule is one of the acaulescent species in South Africa. The other one is Crinum minimum.
C. acaule flowers open late in the afternoon, usually at dusk. The flowers are strongly fragrant and the anthers heavily covered in pollen. The pollinating agents are likely to be varied but probably include nocturnal moths.
Crinum acaule flower buds. The bud on the left opened at dusk on 18 October 2003.
The new flowers of this species typically come into flower at dusk or in the early evening.
C. acaule still occurs on strips of coastal grassland adjacent to exotic forests. The grassland is cut periodically as part of firebreak procedures and this creates ideal conditions for the plants to flower. This habitat is also periodically rotovated (lightly plouged) to assist with weed control. The combination of these two activities mean that there is little recruitment of new bulbs to the populations. Some areas have good populations of young bulbs but in these cases the grassy exotic forest verges are not rotovated. The seeds obtain the chance to germinate undisturbed and the young bulbs to establish themselves in the sandy soil. In some parts adjacent to the Wetland Park extensive spraying of the exotic forest verges with herbicide has taken place. In these areas C. acaule has declined markedly and some once large populations are close to extinction.
C. acaule is one of the few Crinum species that forms bulblets and later large bulbs in response to the cutting or damaging of the bulb plate. Some of the bulbs growing adjacent to exotic forests have been disturbed and damaged by machines used for tree felling. In several instances the damaged plants have produced several new bulbs from the basal plate.
C. acaule flowering is much more erratic in pristine grassland. The bulbs flower poorly when the grass cover becomes dense. Good flowering resumes once more after the grassland has been burnt or well grazed during the later winter months.
The fruit of Crinum acaule is produced at ground level. This seeding habit accounts for the fact that the
species sometimes grows in closely packed clumps.
Crinum delagoense is found in two separate habitats in South Africa. It occurs mainly in arid savanah in the Limpopo River basin and also in coastal grassland in northern Zululand. Its main centre of distribution in Zululand is the Kosi Bay area.
Crinum delagoense is a robust species with particularly beautiful flowers. This specimen was
photographed on 19 October 2003 on the northern Maputaland coastal plain near Kosi Bay.
C. delagoense may grow to very large sizes and some bulbs growing near Kosi Bay have huge umbels containing sixty or more flowers. This species, like C. acaule does not require rainfall to stimulate flowering but good early summer rains in October usually result in mass flowering. The peak of the flowering season is usually early summer, late October and November.
C. delagoense usually grows in scattered groups of a few large bulbs and some small ones, in the vicinity of the parent plants. Occasionally extensive colonies of these plants are found such as in the
Venetia Mine area in Limpopo Province.
In the Limpopo River basin bulbs flower erratically. Flowering is usually at its best in the year following good rains the previous summer. Some of the larger bulbs flower even during droughts, but most only produce leaves or else remain dormant during severe droughts.
Crinum delagoense in flower on the Maputaland coastal plain south of Kosi Bay. The usual flower form of the species in this area has prominent coral pink stripes on the petals.
C. delagoense has some of the most attractive fruits in the genus which resemble pink apples. These are produced in December when the main summer rains are usually well under way. Each capsule contains numerous seeds and these are distributed by water runoff after rains. The fleshy seeds are very hardy and some may survive several months without rain before they germinate. C. acaule and C. foetidum produce a few large rugose seeds in contrast to the very large number of C. delagoense seeds.
Seedlings can be numerous during years of high rainfall but many of the young bulbs are lost to severe and prolonged droughts before they reach maturity. Trampling by livestock also results in the loss of young bulbs in the densely settled areas of the Zululand coastal plain.
C. foetidum is a spectacular species with very broad long leaves and large strongly fragrant white flowers borne in big umbels. The petals usually have pale rose longitudinal stripes. The plant derives its name from the foetid smell produced by the leaves when they are bruised or crushed.
Crinum foetidum inhabits mostly the arid savanah in the Western Limpopo River Basin in the
South African part of its distribution range. The flowers are very large and strongly fragrant.
C. foetidum is found in the western section of the Limpopo River Basin in the South African part of its distribution range. The plants grow in arid savanah, usually in deep red sand in association with Combretum species. This species requires good rainfall in order to flower well and these conditions are only met once every five or six years. During droughts the plants remain dormant.
If some rain falls during drought years the very large C. foetidum bulbs may produce an umbel of flowers when the bulbs are in a leafless state. This unusual habit has not been observed in other South African Crinums and seems to represent an adaptation to an arid environment with unpredictable rainfall.
C. foetidum has some of the most spectacular leaves produced in the Genus. These may be up to two metres in length in the case of some of the very large bulbs.
.Crinum foetidum has characteristic beaked fruit. The Crinum species only sets large amounts of seed
during years of good rainfall. Its habitat is subject to prolonged and frequent droughts.
C. foetidum sets seed in December usually at the peak of the rainy season. Seeds are distributed by water runoff. This species is sometimes found growing in clumps consisting of mature bulbs and younger plants produced from seeds that have been liberated close to the adult bulbs.
Some young bulbs succumb in severe droughts, but as this species restricts most of its flowering and seeding to years of good rainfall many young plants are ensured a good chance of survival.
The three Crinum species discussed in this newsletter all grow well in large containers. The ideal planting mixture consists of 1/3 sandy soil, 1/3 silt or fine riversand and 1/3 sieved well rotted leaf mould. Plants should be grown in direct sunlight or lightly dappled and deeply watered at regular intervals whilst the plants are in active growth and flower. Bulbs need to be kept dry in the winter.
The three species set seed in cultivation but usually require hand pollination with cotton buds. Cross pollination is usually required for seed production and, consequently, several bulbs of one species should be grown in the same container.
Seeds are easily germinated by keeping them in a shallow dish in shade until they sprout a root. They can then be lightly pressed into the germination mix with the root pointing downwards into the soil. The ideal germination mixture is the same medium in which the mature bulbs are cultivated. A young bulb is usually formed within two months and has usually produced its first set of leaves by the end of the summer growing season.
Crinum seeds and young bulbs are available through Penrock Seeds and Plants. Plants are available throughout the year and seeds from December to March depending on the species. Stocks of seeds vary from one year to the next dependant on the harvest conditions.
FURTHER READING
Craib C. and Blackmore A. Crinum acaule in Zululand South Africa.
Herbertia Volume 52, 1997 : 72 – 80.
Craib C. and Brown L. Some Bulbous Flora of the Limpopo River Drainage Basin in the
Northern Province. Herbertia Volume 54, 1999 : 129 – 132.
Verdoorn I.C. The Genus Crinum in Southern Africa. Bothalia 11 No. 1 and 2, May 1973 : 27 – 51.