HAEMANTHUS AVASMONTANUS IN THE MOUNTAINS NEAR WINDHOEK IN CENTRAL NAMIBIA.
Text by Charles Craib
Photographs by Connall Oosterbroek.

SUMMARY.
Haemanthus avasmontanus has, until recently, only been formally known from the type description by Kurt Dinter in 1923. This description was drawn up from a collection in the Auasberge east of Windhoek. The plants were also known from a second collection by Dinter in the Auasberge and another by Dinter at Dobra in the Otjihaveraberg just north of Windhoek. The third collection was made by Rusch in the Khomas Hochland Mountains west of Windhoek.

The four original collections seemed to suggest that the species may occur more widely in the mountainous areas of central Namibia. However no further records were added although at least two people, a well known horticulturalist and an amateur botanist, had reported seeing plants in the vicinity of the type locality and at Dobra, respectively.

A concerted effort was made to find the species in 2009 and 2010 and this newsletter concerns the rediscovery of the haemanthus as well as an account of its natural occurrence.

NEWSLETTER.
BACKGROUND TO THE REDISCOVERY OF HAEMANTHUS AVASMONTANUS.
It sometimes happens that plants that are lost for a long time from the botanical record are rediscovered by accident. It is however more usual for people with field knowledge of the genus concerned to find them once again. Experience with locating specific plants allows botanists, both professional and amateur, to narrow down the search areas of what are sometimes vast habitats such as the mountains around Windhoek where H. avasmontanus was previously recorded.

Summer growing Haemanthus species sometimes grow in full sun where their habitats are wet or saturated for long periods. The typical example here is Haemanthus montanus which often occurs on clayey soils in moist places that are temporarily inundated during the summer. The opposite is true with Haemanthus humilis subspecies humilis and Haemanthus humilis subspecies hirsutus which usually grow on shady, well drained south-facing rocky outcrops in situations where there is thin soil.

I believed that Haemanthus avasmontanus was likely to inhabit moist steep south-facing hillsides or cliff ledges in situations likely to remain wet for longest after rainfall. This concept, which guided searching for the plants, narrowed the areas that were examined considerably. In certain mountainous areas there was no suitable habitat that conformed to the search concept and these could quickly be eliminated allowing for more time to be spent in places that might prove productive.

There were several motivations for relocating H. avasmontanus. Bulbous plants that are restricted to mountainous areas are often susceptible to habitat changes. This is particularly so where there are alterations in stocking practices, for example a transition from cattle ranching to goat farming. This Haemanthus, if rediscovered, would be an ideal plant to feature in a book for which I am currently conducting research. The various chapters will account for the ways in which habitat changes have affected Southern African bulbs and succulents. Equally important was to contribute original observations and autecological research data to Piet Vorster’s magnum opus on Southern African Amaryllidaceae. This thorough and magnificently illustrated work is at an advanced stage of preparation and was, until my recent research, missing data on H. avasmontanus. Not only has Piet been supplied with a good deal of original information on the plant for inclusion in his book but the photographic record has allowed for the preparation of several water colour paintings of the leafing and flowering stages of the bulbs. A selection of these will be included in Piet’s book.

THE INITIAL RESEARCH.
The initial research, consisting of two days spent searching for H. avasmontanus, took place in the second half of May 2009. This was at the beginning of the dry winter after a good summer of copious and prolonged rains in the Windhoek area. The group involved in the fieldwork consisted of an amateur botanist resident in Windhoek, Bob Webb and his partner Antoinette (Tony) Yoko from Tucson in the United States, Dawie Human from Bloemfontein in the Free State and myself.

With only two days available it was decided that the first would be spent searching in the mountains near Aris south of the Auasberge type locality and the second near Dobra (Brakwater) north of Windhoek where one of the syntypes had been collected.

The search on the first day proved to be fruitless. It was not known at the time but the mountains had very little suitable habitat. They lacked the multiple niches associated with seasonal watercourses near mountain summits, which as it transpired later, are the ideal places to find the haemanthus. The excursion arranged for the second day took place in the southern section of the Otjihaveraberg near Dobra. This mountain range, that runs from the south to the north, starting only a few kilometres from Windhoek, is convoluted on its summit, full of larger and smaller sized gorges that flank the sides of small seasonal streams. These flow for short periods after good rainfall in the summer months, when the haemanthus is in active growth.

An area of several square kilometres on the summit of the mountain was searched. These slopes were too arid for the haemanthus, it seemed, but many clumps of Psudogaltonia clavata were seen, their leaves already brown and sere as the plants had entered dormancy during the dry autumn. A decision was made to search much of the length of a gorge that ran across the summit of the mountain form east to west. Conditions were ideal for walking along the watercourse as it was already dry after the autumn drought. I was accompanied by Dawie Human and we each looked at different parts of the habitat as we progressed along the gorge. At one point we passed through a narrow defile flanked by cliffs. Several dried sienna brown leaves caught my attention conspicuous against the dark brown soil distributed in pockets across the broader ledges. Several places where leaves were seen were inaccessible but we managed to reach some. Dawie was also able to take a number of photographs. We felt certain that the dry leaves belonged to dormant H. avasmontanus bulbs but we needed to wait impatiently until well into the following summer before it was appropriate to plan another visit.

This single Haemanthus avasmontanus has managed to take root in a thin soil- filled crack on a vertical cliff face. Bulbs such as this one are laterally compressed enabling them to grow in very narrow spaces.

Psudogaltonia clavata is widespread and common on many parts of the Otjihaveraberg, growing in clumps. The bulbs are found on arid sunny northern and western slopes and are frequently encountered in the general area where Haemanthus avasmontanus occurs.

PHOTOGRAPHING THE PLANTS AND FIELD RESEARCH CONDUCTED EARLY IN 2010.
A further visit to the site took place at the beginning of 2010, in early February. Dawie Human and I were accompanied by Connall Oosterbroek, a well known plant and natural history photographer. The trip was also planned to photograph Monsonia marlothii in west central Namibia and Monsonia mossamedensis along the coast north of Swakopmund near Henties Bay.

The Windhoek area had once again experienced good and regular rainfall in the last two months of 2009 and January 2010. The countryside was very green as we approached the Otjihaveraberg and our hopes were high that we would find that the putative H. avasmontanus bulbs were in leaf and better still, also in flower. We took a short cut across the top of the mountain in a direction that would lead us directly to the gorge. When we reached the place where we had seen the dry leaves on the cliff ledges the previous May, we were very pleased to see that the plants were in fact H. avasmontanus. The bulbs were much more numerous than we supposed, growing gregariously on the broader cliff ledges or else singly and in smaller groups where space was more confined. The leaves are a distinctive lime green making them easy to spot on the dark background of the cliff ledges and soil.

A full account of this species in its habitat as well as the interesting autecology of the bulbs is given in a paper titled “The Rediscovery of Haemanthus avasmontanus (Amaryllidaceae) in Namibia”. (Craib, Charles, Herbertia Vol. 64, in press). A few of the details in the Herbertia paper are summarised in this newsletter and additional discussion is also provided.

Several hours were spent searching the section of the gorge where the bulbs were originally seen and elsewhere. They were found in a number of different habitat niches nearly all of them on south-facing aspects of the mountain. Perhaps the most surprising finding was that the species sometimes inhabits crevices and narrow ledges on sheer rock faces. Such a colony is featured in one of the photographs that accompanies this newsletter.

It was interesting to notice that hardly any plants were encountered on the sunny northern slopes. Those that there were grew well out of direct sunlight in shaded rocky recesses, usually at the back of small caves. These places were clearly well irrigated after good rainfall since they also contained banks of moss and ferns.

Connall Oosterbroek took numerous photographs of the plants and these could be associated with the descriptions of the different niches in the habitat. The bulbs were confined entirely to rocky places, mainly sheer or broken cliff faces and were largely absent from steep grassy slopes free of rocks. It seems likely that competition from dense grass and shrubs confine the H. avasmontanus to the sites they occupy but further data is needed from other colonies elsewhere for this to be confirmed.

A group of Haemanthus avasmontanus crammed into narrow soil-filled cavities on a broad cliff ledge. The single leaved plants are juveniles of various ages whereas those with two leaves are adult flowering size bulbs.

A developing Haemanthus flower and flower stem photographed about a week after emerging through the soil. At this stage the tip of one of two leaves had also just started to emerge.

THE GROWTH CYCLE AND POPULATION SIZES.
H. avasmontanus sprouts leaves and flowers with the commencing of the main summer rains around Windhoek. This is generally in the months of November and December. A curious phenomenon which is not yet understood is that the plants flower very erratically and this is not necessarily associated with good rainfall. Only a few bulbs were noted to have flowered on the occasion of the site visit in February 2010 and none of the plants that had flowered had produced any seed. It seems probable that the bulbs, which are the smallest of any of the Haemanthus species, need to spend several years building up reserves before flowering. A mass flowering event is then likely to be triggered by abundant rainfall. Young bulbs in the different colonies were often seen at roughly the same stage of development. The species produces only one leaf for the first few years after germination from seed, and leaves of more or less the same size can be used to distinguish the young bulbs into various age grades.

H. avasmontanus is locally well represented where it grows and there are few additional niches that can support further bulbs. This is particularly so where the plants throng narrow ledges on sheer cliff faces. Erratic flowering in habitat has the secondary function of ensuring that not too much seed goes to waste in a rather arid environment.

H. avasmontanus population sizes at the site investigated were governed entirely by the number of south-facing cliffs with enough depth of soil for the bulbs to establish themselves. A multiplicity of habitat niches permitted a huge variation in numbers of bulbs per niche. These varied from a few bulbs to several hundred.

THE STATUS OF THE HABITAT.
The farm where the research was carried out is used mainly for cattle ranching. Cattle were found to have no effect on the Haemanthus as they graze mainly on grassy hillsides and in valley floors with good grass cover. A transition to goat farming would quickly cause the bulbs to decline as many of the colonies on broken cliffs would be accessible to grazing goats. The Haemanthus bulbs are likely to be poisonous to grazing stock but would nevertheless be trampled whilst goats were seeking grass to graze and shrubs to browse.

Parts of the northern and central Otjihaveraberg are used for game ranching and, should H. avasmontanus be found there, it would be interesting to contrast this data with that from the southern part of the mountain range. It is also significant to note that the status of the species cannot be determined at present as there is insufficient locality data on which to base conclusions. It may however be that the haemanthus is well represented in habitats similar to that where the research was conducted.

ACKNOWLEDGEMENTS.
I would like to thank Connall Oosterbroek for taking many good photographs of the plants in habitat which have been used to illustrate this newsletter, and the paper in press, to be published in Herbertia. These will also be used to illustrate the section on H. avasmontanus in my book on habitat changes.

Dawie Human is thanked for his company on various filed trips in search of the plants and for taking photographs which form a valuable part of the photographic record.

Piet Vorster edited the text and refereed the Herbertia paper and is thanked for his valuable inputs in this respect.

Gerhard Marx is thanked for painting the beautiful watercolour painting of a group of H. avasmontanus on a rock ledge in the Otjihaveraberg. This features in the Herbertia paper and will also be used in the book on habitat changes.

REFERENCE.
Craib, Charles. The Rediscovery of Haemanthus avasmontanus (Amaryllidaceae) in Namibia. Herbertia Volume 64, in press.