December 2010

SUMMARY.
An extra newsletter has been written for December 2010. It concerns an account of the newly described Ledebouria mokobulanensis. Very little is currently known about this plant, one of several species that grow in mist belt mountainous areas. The majority of these species await formal description and are in several cases narrow endemics known from one mountain range. L. mokobulanensis is one of the most beautiful of all the dwarf Ledebourias on account of its unique corrugated cryptic leaf which renders the species well camouflaged in habitat.

This particularly handsome Ledebouria mokobulanensis has a densely pitted leaf with a deep purplish brown bloom.
This foliage is well camouflaged on damp soil making it sometimes difficult to tell where the leaf ends and the soil begins.

THE DISTRIBUTION OF LEDEBOURIA MOKOBULANENSIS AND ITS HABITAT NICHE.
L. mokobulanensis occurs in a limited area of the Drakensberg escarpment east of Lydenburg. The present known distribution is from the vicinity of the Mokobulaan plantation in the south east to Formosa Mountain in the north east. The altitudes of the habitats frequented by the plants in this area range from 2000 metres to just over 2200 metres. The species may well have occurred at lower altitudes, in the mist belt to the east, but this area is now heavily utilised for exotic timber plantations.

The habitats occupied by the bulbs are well preserved and subject to very little external pressures such as grazing. Formosa Mountain is moreover a formal conservation area. Some of the mountain top grassland, mainly in the flatter valley floors, is used for grazing cattle and recreational trout fishing. The western part of the Mauchsberg, above the Long Tom Pass is extensively used for potato crops, but this is immaterial to the Ledebouria which is apparently absent from this rocky, very well drained habitat, in effect much more arid than the eastern area.

L. mokobulanensis is thinly scattered across short mountain summit grassland and grows in well drained friable peaty soil. The bulbs are best represented in places that remain seasonally damp throughout the summer usually occurring in depressions on steep slopes. Small populations, which are often isolated from one another, occur in drier places often on and round about mountain saddles. The bulbs avoid rocky places with thin grass cover, the typical habitat of Brachystelma stellatum, which is commonly found on the summit of the Mauchsberg plateau.

The Ledebourias are dependent on winter grass fires to clear the habitat for their optimum growth the next spring and summer. Most of their growth is in October and early November, accomplished in a period of 6 – 8 weeks. The post grass fire period from late December onwards, for the rest of the summer, is a time when the bulbs are usually well screened from direct sunlight by the new growth of the surrounding grass.

These Ledebouria mokobulanensis leaves represent the opposite ends of the spectrum. The lime green leaf, almost free of pigments, is conspicuous whereas the more conventional, regularly encountered leaves, are cryptic.

Ledebouria mokobulanensis sometimes grows in grass tufts. These plants are fully dependent on grass fires which clear the dead material
and allow leaves to emerge. These grow briefly in the early summer before they are shaded out by new grass blades.

Brachystelma stellatum is seldom if ever found growing together with Ledebouria mokobulanensis on the Drakensberg east of Lydenburg.
It is commonly found growing with the undescribed rounded leaved species on the Steenkampsberg.

POPULATION SIZES AND THE GROWTH CYCLE.
L. mokobulanensis is in leaf from October to February and flowers shortly after the new leaves emerge in October and early November. Flowering is very erratic and at one locality that has been studied for the past two flowering seasons, only about a third of the bulbs flowered. Pollination is also irregular and spent stems of withering flowers are a regular occurrence. The paucity of flowering and lack of pollination probably explains the small sizes of most groups of plants which are widely scattered across the mountains. Sometimes groups of 4 – 12, occasionally more bulbs, are found. These often contain a number of juveniles with leaves of approximately the same size indicating a good seed set and germination of these seeds in some years. The species is overall rather rare and absent from a good amount of seemingly ideal habitat.

L. mokobulanensis is amongst the limited numbers of Ledebourias that have small bulbs. All of these are confined to mountainous mist belt areas, the greater majority endemic to eastern Mpumalanga. In the case of L. mokobulanensis and some of the others there is always a source of moisture in the habitat even during the winter dormancy from April to September. In the summer moisture is provided by mist and rain. Mist, which is frequent on the Drakensberg condenses as soft penetrating rain and augments the moisture received directly from conventional rainfall. Melted frost, fog and occasional snow in the winter ensures that the habitat receives some moisture in the dry season.

The manner in which mists irrigate the habitat is shown clearly in the photographs which accompany the newsletter which were taken in misty conditions on 30 November 2010. Thick swathes of mist ascended upwards from the lower and central parts of the mountainous habitat. It condensed on rocks, grass blades and the ground itself. It also fell as fine rain. An abundance of cobwebs throughout the habitat, adjacent to the Ledebourias, assisted the process further.

The habitat occupied by Ledebouria mokobulanensis on the Drakensberg east of Lydenburg. This photograph was taken on 30 November 2010 in the afternoon with intermittent swirling mists.

The short mountain grassland frequented by Ledebouria mokobulanensis. The bulbs avoid the rocky places such as those in the foreground and background occurring instead in the moist saddles and depressions on the mountain.

A typical heavily pigmented deeply pitted L. mokobulanensis leaf, is well camouflaged in its gritty habitat as a Lithops species.

CHARACTERISTICS OF L. MOKOBULANENSIS FOLIAGE.
L. mokobulanensis is unique in the genus in that the leaves bear pits or corrugations on their surfaces often densely pigmented with purplish brown or reddish brown. This pigmentation may also be dark green on an otherwise lime green leaf. The sizes, shapes and patterns of corrugations on the leaves are astonishingly variable in some populations whereas in others they are more uniform. In the case of most plants the leaves are suffused with purplish brown.
The bulbs usually produce one leaf, occasionally two. These range from extremely cryptic to relatively conspicuous. The plants with a reddish brown or purplish brown bloom to their leaves and similar but darker colours in the corrugations, are usually difficult to spot. These hues and patterns mimic the colours of the sombre peaty soil, blackened remnants of burnt grass stalks and fragments of grit that are frequent in parts of the habitat.
The lime green leaves are usually conspicuous and easy to see, a complete contrast with the other types of foliage produced by these plants. L. mokobulanensis has the most variable foliage amongst all the Ledebouria species. This phenomenon remains an enigma and requires further study.

Swirling early summer mists ascending the Ledebouria mokobulanensis habitat in dense swathes.
These mists condense periodically as soft penetrating rain.

LEDEBOURIAS OCCUPYING EQUIVALENT HABITAT ON THE STEENKAMPSBERG.
The Steenkampsberg is similar to the Drakensberg escarpment near Lydenburg and is situated some 50 kilometres to the west, as the crow flies. The highest point on the mountain lies at 2231 metres and most of the mountain top Ledebourias occur at 2000 – 2200 metres.

The three main species which grow on the Steenkampsberg in equivalent habitat to L. mokobulanensis, are all undescribed and are currently under study by Ledebouria expert Andrew Hankey at the Walter Sisulu Botanic Garden in Roodepoort near Johannesburg. One plant, formerly thought to be Ledebouria saundersonii, has been incorrectly assigned to that species and is now known informally by the name “Ledebouria steenkampsbergensis”. This plant occurs in gritty pockets of sandy soil between rocks. It often grows together with a densely pubescent form of Haemanthus humilis subspecies hirsutus. Another plant found by Judd Kirkel, a well known plant explorer from Johannesburg, occurs in similar rocky terrain mostly at lower altitudes and is informally known as “Ledebouria purpurea”. This plant grows gregariously and has purple flowers and erect bright green leaves. Another plant, incorrectly assigned to Ledebouria monophylla, also requires formal description. It has several similarities to L. mokobulanensis and also some differences and will be described in due course by Andrew Hankey. The names “Ledebouria steenkampsbergensis” and “Ledebouria purpurea” are simply used at the moment for convenience and presage the formal publication of the 2 new species. The plant incorrectly assigned to L. monophylla is the subject of the remainder of this essay. It is simply referred to here as “Ledebouria species with a rounded leaf, Steenkampsberg” or else an abbreviated version of this cumbersome description.

Ledebouria mokobulanensis leaves blend well with the colour of peaty soil and burnt grass in the post winter grass fire habitat, once the leaves sprout, prompted by the first rains of the summer. The characteristic umbrella-shaped inflorescence of this species is diagnostic.

An unidentified species of Sundew plant (Drosera species) adjacent to cobwebs laden with moisture droplets after heavy mists.
Cobwebs together with other natural objects trap moisture irrigating the Ledebouria mokobulanensis habitat.

LEDEBOURIA SPECIES WITH A ROUNDED LEAF, STEENKAMPSBERG.
In his M. Sc. thesis 1993 (215 – 222) Fanie Venter uses his concept of Ledebouria monophylla to refer to plants with a single rounded leaf from various parts of Mpumalanga. These Ledebourias are associated with mist belt short mountain grassland such as that at the Mount Sheba Nature Reserve near Graskop. The plants on the Steenkampsberg were assumed to belong to this concept of L. monophylla and appear to be the same entity as those found elsewhere such as Mount Sheba. Subsequent fieldworkers operated with this concept for example Craib, 1999: 44.

It was later correctly pointed out by Ledebouria expert Andrew Hankey (2005 – 2006, 91) that L. monophylla is a well defined species concept that refers to a dwarf single leaved plant known from mountain escarpment grassland at Paradise Camp near Graskop. Hankey also drew attention to the fact that the Steenkampsberg plants are closer to Ledebouria saundersonii than L. monophylla.

Fanie Venter revised his original views in his Synopsis of the Genus Ledebouria (2007 - 2008, 128) taking the view that the plants in the mountain summit grasslands of the Steenkampsberg are closely related to L. monophylla but without citing reasons for his opinion. In summary we are left with two different opinions, Andrew Hankey believing that the plants are close to the concept of L. sandersonii and Fanie Venter considering that their nearest affinities lie with L. monophylla.

A full account of the autecology of the Steenkampsberg rounded leaf Ledebourias is given by Craib (2005 – 2006: 83 – 89). Since writing this paper I have now changed my views and consider that these plants have many similarities to L. mokobulanensis at the level of autecology. The history of the debate surrounding the placement of Steenkampsberg plants will all enrich the final decisions that are taken when they are formally described. The final part of this account focuses on the comparative autecology of L. mokobulanensis and the rounded leaved species on the summit of the Steenkampsberg.

L. mokobulanensis and the rounded leaved species occupy equivalent habitat niches on the summit of the Drakensberg near Lydenburg in the case of the former and the top of the Steenkampsberg in the case of the latter. Both plants have small bulbs with a similar structure and are dependent on high levels of habitat moisture throughout the summer growing season. They are also dependent on melted frosts, winter fogs and occasional melted snow in the dry season to prevent desiccation.

A densely pubescent broad leaved variant of Haemanthus humilis subspecies hirsutus is commonly encountered growing near or together with all the Ledebouria species on the Steenkampsberg.

Both species rely on dry season grass fires to clear their habitats of dense moribund grasses and herbs. This is particularly so in the case of L. mokobulanensis which is a strictly grassland plant. The rounded leaved species on the Steenkampsberg not only occupies several distinct niches in the true grassland on that mountain but is also commonly encountered on rocky outcrops which catch the mist. These plants are also much more abundant than L. mokobulanensis and set seed regularly during good flowering seasons.

L. mokobulanensis and the Steenkampsberg entity usually have only one leaf, more rarely two. Occasionally L. mokobulanensis produces a leaf without pits (corrugations) on the surface and in these instances the plants are virtually indistinguishable in bulb and leaf from the Steenkampsberg rounded leafed species.

This portrait of the undescribed rounded leaved Ledebouria species on the summit of the Steenkampsberg shows a plant growing in a
soil-filled rocky niche on a cliff ledge. This type of habitat on the Drakensberg, is shunned by Ledebouria mokobulanensis.

Could it be that the Steenkampsberg plants are a subspecies of L. mokobulanensis? This depends on how workers and researchers develop and use the concepts of subspecies, variety and form in their circumscription of variation in the genus Ledebouria. This step has already been taken in the description of Ledebouria ovatifolia subspecies scabrida (Craib 2008 – 2009: 243 – 244) and represents a change in the production of knowledge in mainstream Ledebouria taxonomy.

It is clear that the study of Ledebouria and an authentic placement of species in the genus, can only be accomplished by extensive fieldwork. In practice Andrew Hankey is the most knowledgeable person in this respect in South Africa and many of the decisions will probably rest with him.

The placement of the Steenkampsberg plants is at present full of loose ends, a true enigma metaphorically speaking.

The habitat of the undescribed Ledebouria species with rounded leaves on the western summit slopes of the Steenkampsberg.
This photograph was taken at dusk with mists lifting from the mountain summit on 30 November 2010.

FUTURE READING.
The full debate about the Steenkampsberg Ledebourias and other related matters is covered in the references that follow. It would be useful for readers to consult these if they wish to consider the background to the themes elicited and discussed in the text.

REFERENCES.
Charles Craib and Laurian Brown. The Ecology and Cultivation of Rare and Little Studied Ledebourias in South Africa. Herbertia Vol. 54, 1999: 43 – 50.
Charles Craib. Ledebouria species affinis Ledebouria monophylla (Hyacinthaceae) in habitat east of Roossenekal, Mpumalanga, South Africa. Herbertia Vol. 59 and 60, 2004 – 2005, 2005 – 2006: 83 – 90.
Charles Craib. Ledebouria ovatifolia subspecies scabrida in Kwazulu Natal, South Africa. Herbertia Vol. 63: 243 – 254.
Andrew Hankey (Post dated) Addendum: Taxonomic Note on the Identity of Ledebouria monophylla. Herbertia Vol. 59 and 60: 91.
Fanie Venter. 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.
Fanie Venter Synopsis of the Genus Ledebouria, Roth (Hyacinthaceae) in South Africa. Herbertia Vol. 61 and 62, 2007 – 2008: 85 – 155.