TWO CRYPTIC AUTUMN AND WINTER GROWING AND FLOWERING ORNITHOGALUM SPECIES, FROM THE SUMMER RAINFALL NORTH WEST PROVINCE.

Light and shadow play a significant role in rendering these three Ornithogalum leaves cryptic amongst exposed dolomite rocks. The photograph was taken west of Malopo Oog on 9 July 2009.

Charles Craib photographed in the Ornithogalum habitat west of Malopo Oog on 9 July 2009. This photograph was taken about 20 minutes before sunset at a time of day when winter temperatures begin to drip sharply.

The surface of the Leeupan Ornithogalum leaves is often quite sticky. In this photograph calcrete derived sand particles can be seen clinging to the leaves.

Charles Craib photographed in the Ornithogalum habitat on 8 September 2006 with Leeupan in the distance.

SUMMARY

The western parts of South Africa’s North West Province consist of mostly flat or gently undulating high altitude grassland or scrubland. Rainfall is confined to the summer and early autumn from early October until late April.

Two peculiar dwarf Ornithogalum species, which are currently undescribed, with cryptic greenish black leaves have been found in the Delareyville and Lichtenburg districts. They respond to autumn rains in March and April and continue to grow in May and June. The single leaf starts to wither around about the time of the winter equinox in late June and the plants flower in July and August. Temperatures at night are often well below 0°C from late May until mid-August in the plants’ habitat. This peculiar growing and flowering habit may be a relic from a different climate. These two plants are discussed in some detail in the newsletter.

NEWSLETTER

THE HABITATS OCCUPIED BY THE TWO ORNITHOGALUM SPECIES.
The Ornithogalum species from the gentle slopes around Leeupan near Delareyville in the North West Province grows in calcrete soil with a high grit and fine sand content. The plants occur mostly on stony north-facing slopes where the grass cover is at its thinnest.

The species from west of Malopo Oog in the Lichtenburg district is confined to very low ridges of weathered dark grey dolomite. They also occur on exposed sheets of rock that are a regular feature of this countryside. The bulbs grow in soil-filled cracks in the rock as well as in larger cavities. The soil consists of a rich moisture retentive loam.

At present the two Ornithogalums are known from a very small amount of habitat. They were not found in ideal habitat around Barberspan, a much larger freshwater pan immediately south of Leeupan. The reason may be related to the introduction of large numbers of ostriches in recent times in the Barberspan Nature Reserve. These huge birds feed on many different bulbs and corms which occur near the surface of the soil.

THE ORNITHOGALUMS AT LEEUPAN.
The plants at Leeupan were found by accident in mid-May whilst searching for Daubenya comata which has been recorded sparingly in the Barberspan Reserve. There is limited suitable habitat around Leeupan since much of it consists of seepage areas with sedge beds or dense grasses which grow in concentrations within a stone’s throw from the water’s edge. The north and west-facing slopes around the pan have the largest amount of suitable habitat. These slopes have a sparse cover of short grasses and their stony surfaces are rich in sun loving geophytes and succulents.

The Ornithogalum bulbs are deep seated in the ground with a long bulb neck usually varying between 6 and 7 cms from the top of the bulb to the point where the leaf emerges from the soil. The plants are widely scattered across suitable habitat either occurring singly or in small groups of 3 – 10. Groups of plants are usually found in places with the most small stones and are virtually devoid of grass. In these situations there is the least competition from other vegetation and also the best chances are afforded to the seeds for germination.

The surrounding farmland supports cattle as well as other livestock, in small numbers. There are no ostriches. Colonies of porcupines have their burrows on the steepest parts of the north-facing slopes. These burrows are generally in areas with low growing perennial shrubs which are habitats unsuited to the Ornithogalums. Porcupines and other animals have not been noted eating any of the bulbs and it is likely that they are toxic to animals that excavate bulbs, roots and tubers for part of their diet.

Livestock sometimes trample the plants’ foliage during the autumn and winter months but no signs of grazing the leaves have ever been noted. Trampling of the foliage makes no difference to the flowering performance of the Ornithogalum bulbs.

The single leaf blade is mostly 3 – 5 cms long and about a centimetre wide. It is cryptic, the greenish black blending in well with the colour of the soil and, particularly, the dark shadows cast by plants and stones in the harsh autumn and winter sunlight. Nothing is currently known about the distribution of this plant elsewhere in the area but the Delareyville and Ditsobotla districts have numerous seasonal pans which are likely to have good habitat for the Ornithogalums.

ORNITHOGALUMS WEST OF MALOPO OOG.
The Ornithogalum species west of Malopo Oog is apparently confined to a small area of less than 20 square kilometres. The countryside consists of grassland usually with shrubs, mostly the Camphor bush Tarconanthus camphorata. The low ridges and sheets of exposed rock on which these plants are found are littered with loose stones and smaller pebbles. The pustulate leaves with their short ivory coloured bristles are cryptic in habitat, matching almost perfectly some of the colours of the rocks. The shadows cast by the exposed dolomite add further camouflage to the plants.

Many of the Ornithogalums are tightly wedged in rocky fissures or grow in soil-filled cavities on the sheets of exposed rock. They mostly occur singly or in small groups of 3 – 6 bulbs. They share their habitat with Euphorbia davyana and a Rabiea species probably Rabiea albipuncta. Nerine frithii grows in the low lying areas, sometimes in the same place as the Ornithogalums, but is more regularly encountered in moister areas.

The Ornithogalums respond to rains that may fall from late February until late April. They grow throughout the autumn and first half of the winter. By 22 June, the time of the winter solstice, the leaves are fully developed and flower buds start to appear. Leaves of the larger bulbed plants are usually about 4 cms long and just under 2 cms wide. As with the species around Leeupan the leaf is closely pressed to the ground.

The habitat is frequently subject to temperatures below zero degrees Celsius at night during June and July. The flower buds and flowers which appear mostly during the month of July are unaffected by these extremely cold conditions.

The rocky places frequented by the Ornithogalums constitute a harsh sun drenched environment. In these places however there is little competition from grasses which colonise the low lying areas with deeper soil. The district is used primarily for cattle ranching. Cattle cause little damage to the leaves and what damage there is occurs when the animals move across the rocky places to the grasslands where they graze. There is no indication that the plants are grazed or that the bulbs form part of the diet of any of the local animals. Porcupines are common in the area just as they are around Leeupan.

THE FLOWERING AND SEEDING CYCLE.

The two Ornithogalum species flower as the leaf starts to wither in the case of the species west of Malopo Oog and once the leaf is mainly shrivelled in the case of plants around Leeupan. The species near Malopo Oog is usually in full flower in the first half of July and the one around Leeupan in the first half of August.

Seed heads develop during August in the case of the Malopo Oog Ornithogalum and in early September in the instance of the plants growing around Leeupan. The seeds of both species are distributed by wind initially in August and September, which is a very windy time of the year. Once the rains begin, usually in October, runoff after rainfall moves the seeds further afield.

In the case of both Ornithogalums seeds germinate in late summer and early autumn, comparable to the initiation of leaf formation in adult plants. Seedlings are not often encountered on the ridges and rocky outcrops west of Malopo Oog. Survival rates of the young plants appear to be low and new seedlings are most often observed during cool cloudy autumns with high rainfall.

THE STATUS OF THE TWO ORNITHOGALUMS.

The two plants are clearly closely related. The flowers and ripening seeds share a similar structure. The unusual umbel of flowers is virtually the same in both plants and is borne close to the ground. The differences are mainly in the size of the Ornithogalums and their foliage, pustulate and bristled on the plants near Malopo Oog and smooth as well as slightly viscous where the Leeupan plants are concerned.

It is a pity that plant material was not available when Ute and Dietrich Müller-Doblies from Berlin conducted their research on Ornithogalums. Their revision of the Genus (1996), incomplete as it considered only some species, remains to date the most authoritative work on the dwarf Ornithogalums.

CULTIVATION AND PROPAGATION

Both Ornithogalum species are easily and readily propagated from seed. Seeds should be lightly and evenly scattered across the surface of the soil and just covered with about 1 – 2 mm of the growing medium. Seeds germinate well in most soils, either well drained or loamy, and late summer or early autumn is the best time for sowing. A good mixture consists of equal parts of river sand and sandy loam well mixed together.

The propagation medium should be kept moist from the time the seeds are sown until well after germination, allowing time for young bulbs to form. The seedlings should be watered throughout the autumn and winter until the young leaves start to show signs of withering. After this the containers should be kept relatively dry in a protected cool place such as under the broad eaves of a house or at the back of a veranda. They should be exposed to rainfall again early the following autumn or, should the containers be kept in a greenhouse, watered from early autumn onwards.

The two Ornithogalum species are good candidates for ornamental container planting, particularly amongst decorative dolomite rock fragments in earthenware containers.

REFERENCE.

Ute and Dietrich Müller-Doblies. Revisionula incompleta Ornithogalum Austro-Africanorum (Hyacinthaceae). Feddes Repertorium 107 (1996) 5 – 6, 361 – 548.