NAMAQUANULA BRUYNSII IN ITS SEMI-DESERT HABITAT WITH AN ACCOUNT OF THE CULTIVATION AND PROPAGATION OF THE SPECIES.

N. bruynsii bulbs that are going to flower in a particular season respond very quickly to rainfall. These plants push up their flower buds a few days after receiving moisture.

Newly emerged N. bruynsii leaves photographed about 12 days after the bulbs received their first rainwater of the season, in late December. The bulbs that produce only initial leaf shoots skip flowering that season.

SUMMARY.
Namaquanula bruynsii is a dwarf Amaryllid so far only known with certainty from the highest elevations of the Tiras Mountains in south western Namibia. The newsletter focuses on the unusual autecology of this strange species in its remote arid mountain top habitat. A detailed account is also given of the cultivation of the plants and their propagation from seed.

NEWSLETTER.
NAMAQUANULA BRUYNSII ON THE SUMMIT OF THE TIRAS MOUNTAINS OF SOUTH WESTERN NAMIBIA.
N. bruynsii was described recently in 2005 from a collection made in 2001 on the summit of the Tiras Mountains (Snijman 2005: 153-156). The description focused largely on the physical characteristics of the plants and their flowers and there is also an interesting account of the re-circumscription of the Genus Namaquanula. In our view the plant could be an aberrant Brunsvigia. This is discussed briefly in the newsletter.

N. bruynsii grows on the highest part of the Tiras Mountains on the farm Landsberg. This part of the Tiras Mountains lies mostly at an elevation of 1900 – 1970 metres. The plants have thus far only been located twice and it may be that they grow only at 1900 metres or more. These elevations on the mountain would be the most sensible to search first for further records before the lower peaks.

The lower altitudes of the mountain range are characterised by a different flora particularly Aloe argenticauda in the western parts. These places also lack the gently undulating areas found on the summit plateau in the highest parts. This is the habitat frequented by N. bruynsii.

The bulbs are difficult to find and it requires a sensitivity to the right sort of habitat. The highest parts of the mountain, which form a vast area, are drained by sandy rivers which flow briefly only after good rains. There are also occasional very gently sloping washes which remain moist for longest after rain. These are places characterised by deep reddish brown loam. This is the specific micro habitat that is home to the Namaquanulas. A large proportion of this habitat is littered with quartzite rocks and pebbles often packed close together. The bulbs have not been found here and seem rather to be restricted to the areas that are not cobbled with stones.

It is likely that the plants are dormant during droughts and probably do not grow and flower for several years in succession. The apparently limited chances for flowering and seeding coupled with the restricted amount of micro habitat available is likely to explain the overall limited numbers of plants. Further research on this subject is needed however before any conclusions can be drawn as to which factors govern the status of the plants.

THE DISTRIBUTION OF N. BRUYNSII IN ITS MICRO HABITAT.
N. bruynsii occurs in small numbers over a wide area mostly at the edges of the washes or in occasional seepage areas associated with them. The bulbs usually occur in small groups of 3 – 6 but also singly. They range in size from seedlings to mature plants with the greatest number consisting of mature well established bulbs.

The distribution of plants is consistent with dispersal of seeds via runoff after rainfall. It may also be that some of the seeds are distributed by wind. The dry seed bearing inflorescences detach with their stems from the bulbs at about the time the seeds are ripe. The seeds are, however, very large and heavy for the size of the dry brittle inflorescence. They would be likely to fall off quickly from the dry brittle umbel. Further research in the field is required on the mechanism of seed dispersal and it may be found that water and wind are the distribution agents. It is evident however that whatever the method of dispersal seeds land close to the parent plants in the most suitable habitat from them to germinate and develop into young bulbs.

LAND USE PATTERNS IN THE HABITAT.
The summit plateaux of the Tiras Mountains on the farm Landsberg were used for cattle ranching at the time the research was conducted. Evidence of grazing by cattle was present all around the niche occupied by the Namaquanulas.

The tufts of perennial grass are kept short by grazing and the washes are cleared from accumulations of moribund grasses and various herbs. This clear open habitat is ideal for the bulbs to thrive.

Mature Namaquanula bulbs are deep-seated at least 12 – 15 cms below the surface of the soil. They cannot therefore be damaged by the hooves of grazing animals. No indications have been found of the leaves being grazed and it may be that they are poisonous.

The farm Landsberg forms part of the Tiras Berge Conservancy where fauna and flora are preserved and eco tourism promoted. The bulbs can be expected to thrive under these circumstances. There would certainly be deleterious effects to the delicate eco system were land use to be changed to communal farming with herds of cattle, sheep and goats.

THE ENIGMATIC STATUS OF N. BRUYNSII.
N. bruynsii has many characteristics of dwarf Brunsvigias. These are in particular the numerous masses of tightly packed brittle bulb tunics, the regular flowering season in late December and early January, much earlier than for most Hesseas and Strumarias, and the large rounded Brunsvigia-like seeds. These characteristics aside, the autecology is virtually indistinguishable from Brunsvigia species that grow in similar habitats.

It may be that N. bruynsii is an aberrant Brunsvigia and more suitably accommodated in this genus. It may also be from the perspective of the construction of botanical knowledge that the Namaquanula is best classified as an abstract conceptual model for organising data rather than a genus. All these factors it is suggested should be taken into account at the theoretical and practical level in future when assessing the most appropriate placement of this species and whether or not the genus Namaquanula is an artificial construct.

THE CULTIVATION AND PROPAGATION OF N. BRUYNSII.
A decision often has to be made when cultivating bulbs whether they are grown best in a conventional river sand mixture or in soil similar to that found in habitat. Clay soils are often quite unsuitable for cultivating bulbs but some thrive in loams similar to those which are found in the natural habitat. It has been found that reddish quartzite derived loams from the Magaliesberg are ideal for cultivating mature N. bruynsii bulbs and growing young plants from the seedling stage to maturity.

N. bruynsii needs to be kept bone dry during dormancy. This is between early August and the second half of September under cultivated conditions in Johannesburg. The pots in which the bulbs are cultivated are kept on top of a low west facing wall in a greenhouse. Here they are exposed to strong intense sunlight from mid morning until the late afternoon. These conditions replicate those in habitat on the summit of the Tiras Mountains.

The bulbs are taken out of dormancy around 18 December. They are exposed to natural rainfall provided by the thunderstorms in Johannesburg which are generally common at this time of year. The flower buds emerge from about 48 hours to a week after exposure to the first good rainstorm which has drenched the pots.

The containers in which flower buds have started to form are moved to a sunny wall on a veranda where they are protected by an awning from heavy rainfall or hail which destroys buds and flowers. During the 3 – 4 week period when the Namaquanulas are in flower and forming seeds they are deeply watered with rainwater every few days.

Flowering frequency is variable from one year to the next. Twenty four flowering size bulbs usually produce 9 – 14 flower stems each year. Should this be typical of plants in habitat, that receive enough rain at the correct time, it would indicate that about half the mature bulbs flower in a given season.

DEVELOPMENT OF THE FLOWERS, POLLINATION AND SEEDING.
The entire flowering period from the buds pushing through the soil until the ripening of the seeds is about a month.

Flowers are cross pollinated manually at least once a day using cotton buds. Copious amounts of cream coloured pollen is produced which is very readily detached from ripe anthers. The stigmas are only receptive fairly late in the development of individual flowers, usually once the petals have started to reflex.

It is very surprising that pollinating insects are only infrequently seen on the flowers in Johannesburg. These have been a small pollen gathering wasp species which collects large amounts of pollen, forming pollen balls on the insects’ legs.

Seeds develop very quickly after successful pollination in about 2 – 3 weeks. They are 3 – 4 mm wide and are large considering the size of the flowers. The seeds are fully ripe at the time they detach readily from the plants. This is just before the inflorescence becomes straw coloured. Seeds are stored on tissue paper covering small plastic trays until they produce a root a few millimetres long.

Seeds are sown individually 3 – 3.5 cms apart. They usually have a well formed root 2 – 3 weeks after harvesting and are sown at this time, in the second half of February.

The young bulbs and mature plants have fully developed leaves by mid-January. The Namaquanulas remain evergreen during the autumn and winter but the full development of the leaves is completed early in the second half of summer.

REFERENCES.
Craib, Charles. Namaquanula bruynsii in its habitat on the Tiras Mountains of south-western Namibia, with an account of cultivating and propagating this species. Herbertia Volume 59, 2004 – 5: 60 – 69.
Snijman, D.A. A new species of Namaquanula (Amaryllidaceae: Amaryllideae) from Namibia with notes on the genus. Bothalia 35,2: 153 – 156 (2005).

N. bruynsii plants photographed on 6 January 2009 grown from seeds sown in February 2006. None of the 21 young bulbs in this pot had flowered at the beginning of their fourth growing season.

N. bruynsii is shown off to best effect in flower when planted in brick coloured terracotta pots.