Several Ledebouria species occupy specific niches and some are vulnerable to habitat alteration and degradation. Some of them are narrow endemics and there are a number of new species which await formal taxonomic description.
Ledebouria atrobrunnea is a newly described species found in a small area of the western Magaliesberg at about 1300 metres. Another small population has recently been found on the Swartwitpensbokfonteinberg near Northam just within the boundary of Limpopo Province, at a similar altitude.
1. Ledebouria atrobrunnea photographed in mid-winter in the western Magaliesberg, North West Province. The plants are growing in a crack of exposed quartzite. The bulbs are growing partly exposed and are protected by hardened old bulb scales. This species is only known from a small area of the western Magaliesberg and one area on the Swartwitpensbokfonteinberg near Northam in Limpopo Province about 150 kilometres to the north.
The habitat in the western Magaliesberg consists of hilly rocky short grassland. The bulbs grow gregariously wedged in quartzite rock crevices or in open sandy pebbly patches amongst the rocks. The hardened old bulb scales protect the neck of the bulb which is often partly exposed. Grass fires burn regularly through the habitat in the dry winter months and more exposed bulbs are quite often burnt. Fires tend to restrict the plants mostly to rocky niches where the bulbs are only superficially burnt in grass fires.
Plants found growing on the Swartwitpensbokfonteinberg occur on dolomite. The bulbs are rarely exposed above the surface of the soil and grow singly. The form occurring here is much smaller than the Magaliesberg plants with fewer hardened bulb scales. The grass cover is normally thin and as the necks of the bulbs are not exposed they escape the effects of burning.
Grass fires have a significant role in keeping the habitats clear at both localities.
Ledebouria confusa (in ed.) is rather rare and at present has only been recorded from three separate localities. It is found on conglomerate hills east of Pretoria in Gauteng in the Cullinan area. There are two other records also from areas of conglomerate rocks. One is from the conglomerate hills north west of Cullinan and the other from the eastern Waterberg near Vaalwater.
2. Ledebouria confusa (in ed.) is only known from three localities. The bulbs are numerous at the one locality east of Pretoria where they grow on north-facing conglomerate hills. The plants grow and flower well after winter grass fires, in the early summer. Bulbs may be seen in leaf in the foreground with Xerophyta retinervis, a typical pyrophyte coming into flower. This photograph was taken after the first good rains of the summer in late October.
L. confusa, like L. atrobrunnea also has partly exposed bulbs protected by thickened old bulb scales. At one large colony near Cullinan winter grass fires are a regular feature. Most of the bulbs are lightly burnt as they grow in open pebbly areas with little grass cover or in rocky fissures. Flowering is profuse in the early summer after winter grass fires but declines gradually in the inter-fire years as the grass becomes dense again.
3. A close up photograph of the partly exposed bulbs of Ledebouria confusa. This is a typical growth habit of large bulbs of this species.
4. A clump of Ledebouria confusa bulbs photographed shortly before the southern winter equinox on 21 June. The partly exposed bulbs are cryptic during the winter months.
L. atrobrunnea and L. confusa are able to regenerate from the basal bulb plate if they get severely burnt in winter grass fires and after porcupines have eaten the bulbs. These animals tend to chew the bulbs from the top and they detach readily from the bulb plate.
5. Boophane disticha grows together with Ledebouria confusa and its bulbs are also mostly exposed. The photograph was taken just before the winter equinox whilst the bulbs are fully dormant.
Ledebouria hypoxidoides is narrowly confined to the hills around Grahams-town. The bulbs grow in open sandy or stony areas between clumps of bush and grass. This habitat is rather limited and probably accounts for the fact that the species is usually sparse and rare where it is found. It may, however, become numerous in disturbed habitat such as on old sports fields on the outskirts of Grahamstown which has large concentrations of these bulbs. The seeds were originally dispersed from small groups of these plants occurring on an adjacent hillside in typical habitat for the species.
L. hypoxidoides is one of the more unusual Ledebouria species with soft densely pubescent leaves resembling green velvet.
6. Ledebouria confusa is most plentiful near the summits of conglomerate ridges where the rocks are often blotched with canary yellow lichens.
Ledebouria lepida (in ed.) has an unusual growth cycle for a diminutive species. Most small Ledebouria species grow actively and flower in early spring, thereby avoiding competition from herbs and grasses. L. lepida starts its growth cycle in December once the main summer rains have saturated the habitat. The habitat consists of sandy patches over sheets of exposed rock which remain moist throughout the summer. Little other plant life has colonised this niche and most that have are numerous within a small area. Amongst these is a dwarf Eriospermum, the smallest known in the genus, which will need to be formally described.
L. lepida flowers and sets seed at the height of the summer rains, ensuring that the species will always be relatively numerous in its very restricted habitat. Occasionally large numbers of these bulbs are eaten by indigenous animals, it is believed either porcupines or pigs. The habitat is temporarily ruined in the process with piles of disturbed sand where the bulbs were excavated. The habitat is gradually flattened again by heavy rainstorms and numbers of the Ledebourias increase once the habitat reverts to its normal state of level exposed seepage areas.
Ledebouria minima is one of the smallest of the grassland species. It is widespread but is found in small groups or singly in moist grassland. There is a very large population in rocky grassland in western Gauteng. The bulbs have colonised open sandy seepage areas which are frequented by few other plants. The species is much less numerous in the short grassland which surrounds these seepage areas. Competition from other plant species ensures that many of the dwarf Ledebourias can only become abundant in limited areas of a given habitat.
7. Ledebouria minima grows and flowers in early summer after winter grass fires have cleared the habitat. The plant in this photograph is in seed and flower in early November.
8. Typical rocky grassland habitat of Ledebouria minima photographed in western Gauteng after a winter grass fire.
Ledebouria monophylla is one of the most interesting of the dwarf species. It has 1-3 rounded leaves, usually only one, tightly pressed to the ground. The species is an inhabitant of high altitude grassland. The plants grow and flower in early summer but only have the chance to flower well after fires have thoroughly burnt the habitat. A large population in the Mount Sheba Nature Reserve is hidden under mountain fynbos (heathland) for many years in succession. This habitat is periodically burnt when large accumulations of dead brush are ignited in winter grass fires. Huge numbers of plants come into flower after fires but flowering declines rapidly two years after fire has burnt the habitat, as the fynbos starts to regenerate.
Populations of this species north of Dullstroom in Mpumalanga grow in high altitude rocky grassland. The bulbs are found at the edges of seepage areas in open patches between grass tufts. This niche is very limited and sparse and consequently populations of the species are usually small.
One of the most unusual Ledebourias in the Genus is Ledebouria viscosa. The bulbs produce 1-3 blade shaped viscous leaves during the summer months. The sticky leaf surfaces are often covered in sand grains. This species is only known from bushveld with deep sand in the Thabazimbi district of Limpopo Province. Extensive searches in neighbouring districts have not yielded additional records for the species. The bulbs have been gradually declining in some areas owing to habitat degradation caused by too frequent burning and trampling by domestic stock. One very large population of these plants has recently been incorporated into the Marakele Nature Reserve north east of Thabazimbi.
Ledebouria viscosa produces sparse flowers and a limited amount of seed. Recruitment of new individuals to the population is very slow.
CULTIVATION.
Most Ledebourias are readily cultivated in containers. An ideal planting mixture consists of 1/3 riversand, 1/3 silt and 1/3 sieved sandy ordinary soil. Some well rotted sieved compost should be mixed in as well, before the bulbs are planted. The bulbs should be evenly spaced in their containers and should not be planted with their necks exposed unless this is a growth habit of the species. In this respect L. atrobrunnea and L.confusa should be planted with the upper 1/4 of the bulb exposed.
Most Ledebouria thrive in full sun or light shade. Those from high altitude mist belt areas such as L. monophylla prefer morning only sunlight. They should not be exposed to the desiccating rays of the afternoon sun.
Ledebourias should be well watered in spring and summer when they are in flower and active growth. They should be kept dry in winter.
Most species of Ledebourias can endure low winter temperatures and will probably prove cold hardy in some milder areas of the Northern Hemisphere. They will probably not however survive excessive winter moisture.
FURTHER READING.
There is little published work on Ledebouria. The Genus was revised by Mr. Stephanus Venter for his M. Sc. and some new species have been published in Bothalia. Articles on the autecology of the plants have appeared in Herbertia. Some of these references are included below.
Craib C. and Brown L. Ledebouria viscosa, one of South Africa’s most striking and unusual Bulbous Plants. Herbertia Volume 53 1998:49-53.
Craib C. and Hankey A. Ledebouria galpinii (Venter). A rare mountain top mist belt species. Herbertia Volume 53 1998:54-58.
Craib C. Ledebouria atrobrunnea (S. Venter). A new species from the western Magaliesberg in South Africa’s North West Province. Herbertia Volume 53 1998: 59-63.
Craib C. and Brown L. The Ecology and Cultivation of Rare and Little-Studied Ledebourias in Southern Africa.
Venter S. A Revision of the Genus Ledebouria, Roth, (Hyacinthaceae) in South Africa. M. Sc. thesis. Department of Botany, Faculty of Science, University of Natal, Pietermaritzburg, 1993.
Venter S. and Edwards T.J. A revision of Ledebouria (Hyacinthaceae) in South Africa. 1. Two new species. Bothalia Volume 28, May 1998: 15-17.
(This paper describes Ledebouria atrobrunnea and Ledebouria dolomiticola).