The Sonnenberg in south western Namibia photographed from the vicinity of the Orange River. This is home to scattered groups of Strumaria speciosa which frequent the summit area of the mountain.

SUMMARY.
Strumaria speciosa is confined to the south western corner of Namibia and is known from the summits of several tall, rugged and remote dolomite mountains. Strumaria prolifera occurs on an isolated mountain top in west central Namaqualand. Both species are little known in the wild as well as in cultivation.

These two species are unique in the genus with respect to the niches they occupy in their habitats, and the way in which they reproduce. They are also extremely unusual and beautiful subjects for specialist plant collections. This newsletter concerns a discussion of both plants in habitat as well as their cultivation and propagation.

In the seasons when Strumaria speciosa flowers, the leaves and flower buds usually emerge simultaneously.

This photograph of Strumaria speciosa was taken about ten days after the leaves and flower bud pushed up through the soil. The flower stem still had to grow to a length of about 45 cms before all the flowers in the umbel had opened.

STRUMARIA PROLIFERA.
Strumaria prolifera was described in 2005 (Snijman 2005: 21 – 23). The type locality is the Kourkammaberg, a quartzite mountain south of Komaggas in Namaqualand. The plants have so far only been recorded from this mountain where they grow mainly in sand and humus on the ledges of broken south and south west-facing cliffs. The species may well occur in mountainous countryside to the east around Kamkambees, Brakfontein and Meskraal.

The Kourkammaberg reaches an altitude of 540 metres at its highest point. The mountain, its foothills and the surrounding sandy plains are heavily grazed by sheep, goats and donkeys and rock hyraxes inhabit the cliffs on which the Strumarias grow. They are not palatable to any of these animals but would be trampled and destroyed by sheep and goats, were it not for the fact the bulbs grow mostly on cliff ledges. The Strumarias are characterised by very thin leaves that would be readily destroyed by the hooves of grazing animals. The bulbs grow gregariously just below the surface of the soil or level with it, making them particularly vulnerable to trampling. The Strumarias are also cool season growers from May to early September when this part of Namaqualand receives most of its rain.

The outermost flowers on the umbel open first when Strumaria speciosa starts to flower. At this time the top of the stem, supporting the inflorescence, is about three quarters of the way through the process of bending downwards.

THE CLIFF LEDGE HABITAT.
S. prolifera grows in tightly packed groups of bulbs that sometimes occupy an entire cliff ledge. In these situations the plants have no competition from other bulbs or shrubs and the largest groups of plants may contain several hundred bulbs. At times the bulbs grow in pure humus or rock hyrax droppings ranging from fresh to well rotted. The ability of the plants to thrive on ledges with very shallow humus or rotted hyrax droppings allows them to colonise most suitable ledges on the cliffs.

It was originally thought, at the time of the type description, that the bulbs proliferated from the base reproducing via offsets. This was seen as compensating for the sparse flowering habits of the bulbs in nature (Snijman 2005: 21). Recent observations indicate that the plants flower when they receive moisture in the autumn. At these times, which may only be once or twice a decade, the Strumarias flower and seed in profusion. The berries are very large in relation to the size of the plants and flowers, measuring 3 to 4 mm in diameter. They are produced at a time when the cliff ledges on which they grow are already in deep winter shade with little chance for desiccation before germination. The sporadic mass flowering of the plants under ideal conditions and the consequent high seed yield results in the large concentrations of bulbs found in habitat. The fact that the bulbs rarely if ever form offsets has been confirmed with cultivated plants grown under conditions where they are regularly watered throughout the growing season.

The Strumarias are sometimes found growing in scattered groups below cliff faces. In these instances bulbs and seeds are likely to have fallen from above and colonised new areas in the shelter of tumbled quartzite boulders. In these places they are protected from the hooves of grazing livestock.

A group of Strumaria speciosa seedlings from seeds sown on 25 and 27 April 2010 photographed at the end of May. The single leaf characterises young plants for the first few years after which there is a sudden transition to the fan of leaves characteristic of adult plants.

ADAPTATIONS OF S. PROLIFERA TO ITS MOUNTAINOUS HABITAT.
S. prolifera has a number of habits which make it ideally suited to a predominantly cliff ledge habitat. The plants flower prolifically, but at widely spaced intervals, setting abundant seed. The flowering stems are mostly about 20 to 24 cms tall and they persist until well after the seeds have been dispersed. These characteristics ensure that they fall immediately around the parent bulbs increasing the size of the clumps.

The erratic flowering habits of the plants ensure that not too much seed is produced relative to the restricted environments in which the plants grow.

The Kourkammaberg photographed in late August 2009. Strumaria prolifera grows on the ledges of south-facing cliffs of various peaks on the summit of this convoluted mountain.

STRUMARIA SPECIOSA.
S. speciosa is one of the most beautiful of the Southern African Amaryllids. It is found in the south western corner of Namibia, an area that receives predominantly autumn and winter rainfall. Some moisture is also provided by way of fog that reaches the summits of the high peaks of the mountains north of the Orange River, the habitat occupied by the species.

S. speciosa was described in 2005 (Snijman 2005: 23 – 25). It has been discussed in a paper published in Herbertia (Craib 2006: 135) and also in a previous newsletter on this web site (May and June 2008).

The plants were originally only known from the Sonnenberg, the type locality, which is a mountain peak that reaches 994 metres at its highest point. Subsequent to the discovery of plants at the type locality Mr. Ernst van Jaarsveld has found them on the summits of several other mountains to the north and north west. Ernst is Southern Africa’s most accomplished and intrepid botanical explorer and has been responsible for the discovery and description of numerous plants from remote and rugged mountain ranges in South Africa and Namibia. His current interest is cremnophytes, plants which grow on sheer cliff faces or cliff ledges.

Some of the discussion which follows below has been based on details kindly supplied by Ernst who has observed S. speciosa across the full range of habitat niches where it occurs.

Strumaria prolifera flowers are usually a delicate pale shade of shell pink when they first open, turning darker as they mature.

Berries start to develop within a few days after Strumaria prolifera flowers have been pollinated. This habit is visible on the first flower in the middle foreground.

Strumaria prolifera flowers at the same time as the new leaves emerge. The flower stems and leaves are only about half developed at this stage.

S. SPECIOSA IN ITS MOUNTAIN TOP HABITAT.
S. speciosa occupies two distinct habitats. It grows either singly or as small scattered groups of plants on broken dolomite cliff faces or the boulder strewn screes below them. This mode of occurrence is common on the Sonnenberg, the type locality. On the Hohenzollernberg to the north east, which is a higher mountain, the plants grow as they do on the Sonnenberg and also throng broad ledges where they grow gregariously. The Hohenzollernberg has a multiplicity of habitat niches for the Strumarias, but these are more restricted on the Sonnenberg.

The plants are invariably found close to the tops of the mountains on which they grow in south, south east and south west-facing positions. These places capture the greatest amounts of moisture and retain it for longest as the habitat is in shade for the greater part of the winter growing season.

This species flowers very erratically in cultivation. Plants grown in Johannesburg and regularly watered during the autumn and winter months only flower about once every six years. This interval may be much longer in nature, possibly only once a decade. The bulbs produce the longest flower stems in the genus 40 – 60 cms in length and up to 30 individual flowers are produced in each inflorescence.

The bulbs need to build up reserves for a number of successive years before flowering and this furthermore only seems to take place in about mid-autumn, after rainfall. These conditions are probably very rarely encountered in habitat and this is likely to explain the small size of most populations. Nearly all sightings of plants on the mountain tops in south western Namibia are of mature well established bulbs. This suggests that recruitment of seedling plants to the different populations is slow and erratic.

Strumaria prolifera berries photographed at the time they are fully ripe and ready to be shed. At this time they have attained their full size and have a distinctive reddish tinge.

Strumaria barberae from the top of the northern end of the Huib Hoch Plateau in south western Namibia. This species has similar flowers to Strumaria prolifera and the two plants are considered to be related.

FLOWERING, SEEDING AND RECRUITMENT OF NEW PLANTS TO THE POPULATION.
S. speciosa has one of the longest flowering periods of all Strumaria species in cultivation. In Johannesburg this lasts from a few days before mid-March until well into the second half of May. There are no observations as yet of flowering plants in the wild but they are likely to have many parallels to those in cultivation.

Flowering and seeding spans a period of 8 or more weeks with seeds being liberated over a period of over 5 weeks. The seeds that fall from the parent plants therefore have added chances for germination particularly if there are several autumn rain showers.

The seeds are small, rugose and irregularly shaped lodging readily in the soft dolomite soil which surrounds the parent bulbs. This soft soil is a considerable advantage for the germinating seeds since it is water retentive and facilitates the penetration of newly developing roots.

The long stems and large numbers of flowers produced in each inflorescence ensures that seeds are liberated over a period of several weeks. The outermost flowers open first and the remainder at intervals over a period of some 3 weeks. The first flowers to open are already in seed when the last flowers on the scape are in the final stages of flowering. The inflorescence with ripe seeds does not detach from the parent bulbs with the result that seeds are scattered in the immediate vicinity of the parent plants. The occurrence of some young plants, growing on their own, well away from groups of others, needs to be explained. The seeds may be moved during a rain shower or some animal vector may be involved.

CULTIVATION AND PROPAGATION.
Both Strumaria species grow readily in cultivation and make for ornamental and unusual container subjects. The cultivation and propagation of these Strumarias in Johannesburg is discussed below. Much of this information could be used anywhere in the world provided cognisance is taken of the fact that the plants are autumn and winter growing and summer dormant.

STRUMARIA SPECIOSA.
Mature S. speciosa bulbs are grown in large deep terracotta pots about 28 cms deep and 28 cms wide. They are cultivated in dolerite derived loamy soil with some grit content. This medium does not dry out too quickly and helps prevent mealy bug outbreaks when the plants are dormant by encasing them in a covering of dense dry soil.

The long necks of the bulbs are exposed, as they are in nature, to a height of three to five centimetres. Bulbs grown from seeds, and left in the same pot as they mature, expose their necks naturally and consequently it is only when the plants are transplanted that care needs to be taken to ensure that their necks remain above the surface of the soil.

The plants are kept in positions of about 3 hours sunlight during the winter growth period and for the rest of the day they are in shade. The pots are thoroughly watered about twice a week from March to August when the bulbs are in bud and flower and afterwards, in active growth. The leaves start to wither abruptly in about mid-August when day temperatures start to warm up. At this time water is withheld and the plants are kept dry for the duration of the spring and summer. The pots are kept in a cool shady place with good ventilation, much like the resting period the Strumarias would enjoy in their habitat.

POLLINATION OF THE FLOWERS, PRODUCTION OF SEEDS, SOWING SEEDS AND CARE OF THE YOUNG PLANTS.
S. speciosa flowers are manually cross pollinated with the use of cotton buds. The stigmas take some days to ripen and this usually occurs after the petals are fully reflexed. Flowers on the different plants are cross pollinated at least once a day, usually between 11H00 and 15H00 when pollen is light, dry and adheres easily to the sticky lobes on the stigmas.

Seed set is very variable from one plant to the next and also with different flowers on the same plant. The seeds take about three weeks to ripen fully and are harvested at the time they turn a buff or pinkish colour and detach easily from the stem that carried the flower.

The seeds are kept on white kitchen towelling placed on small plastic trays. These trays are kept in a warm, dry room away from direct sunlight. After a few weeks the seeds start to sprout a root and at this time they are planted in the same type of soil used for cultivating adult bulbs. Seeds are sown in small holes with the root fully covered and the seed exposed at ground level. Large deep plastic pots are used, about 25 cms wide and 22 cms deep. In cases where the young bulbs will be transplanted at the end of their second or third growing season seeds are sown about 5 mm apart, and 1 – 2 cms apart where the bulbs will remain for several years before transplanting. In cases where bulbs are not transplanted, seeds are sown three to four centimetres apart. In these instances the bulbs reach maturity from the seedling stage and remain undisturbed.

Seeds sown on 25 and 27 April 2010 had already developed a single leaf 1.5 – 2 cms long by 31 May. The single leaf is characteristic of young plants for the first few growing seasons. The seedlings grow rapidly for about the first month after germination and continue to grow, but at a slower rate, for the remainder of the winter. The young bulbs enter dormancy in the second half of August and the depth and frequency of watering is reduced until the leaves wither. At this time the pots are kept dry in a cool place protected from rainfall until the following autumn.

STRUMARIA PROLIFERA.
S. prolifera is grown in plastic pots about 20 cms wide and 20 cms tall. The planting mixture consists of sandy soil to which a small quantity of fine sandstone derived sand and well rotted finely sieved humus is added. Mature bulbs are planted 5 mm to 1 cm apart with the neck of the bulb just buried below the surface of the soil.

The plants are kept in positions of light dappled shade with about 2 hours direct winter sunlight in the late afternoon. They are watered from the second half of March until the second half of August. The leaves wither rapidly in the second half of August as day length increases and temperatures warm up as the beginning of spring approaches.

In years when the Strumarias flower this is usually from the beginning to the end of April with the flowering peak reached in the middle of that month.

POLLINATION OF THE FLOWERS, THE PRODUCTION AND SOWING OF SEEDS AND CARE OF THE JUVENILE PLANTS.
S. prolifera flowers are cross pollinated for the duration of April when the plants flower under cultivated conditions in Johannesburg. Cross pollination is achieved by using cotton buds and is usually effected once a day in the mid-afternoon. Successful pollination had been achieved with virtually every flower pollinated and ripe berries are usually produced about three weeks after pollination.

The berries are collected once every few days at the time they begin to acquire a reddish tinge and detach easily from the flower stalks. The capsules enclosing the seeds have withered at this time and the uppermost seeds are readily harvested when rubbed lightly between the fingers. The more persistent seeds, lower down, are left for a few more days until they too detach with ease.

The freshly collected seeds are stored on white paper towelling lining shallow plastic trays. It takes about three weeks for the seeds to send out a root and at this stage they are planted. The planting mixture is the same as that for the adult plants and the seeds are sown individually about 5 mm apart. The bulbs are small when mature and as a result the seedlings can be left alone without any need for them to be transplanted.

The young plants are deeply watered at regular intervals throughout the winter. Watering is gradually withheld as the young bulbs start to show signs of entering dormancy in the second half of August. The pots containing them are kept completely dry in a shaded cool place until the end of March or early April the following year when watering is resumed once more.

As an experiment some S. prolifera were grown in conditions of direct winter sunlight. It was found that the plants grew well but that the leaves were considerably less delicate and parchment-like than with those grown in dappled shade. The leaves of bulbs grown only in the sun reached a length of 5 to 7 cms whereas the normal length of the leaves of bulbs correctly grown in shaded conditions varied from 15 to about 20 cms.

It is not yet known whether or not plants grown in conditions of direct autumn and winter sunlight, flower. Too few bulbs have been cultivated under these conditions to make the correct assessment. Their foliage though shorter than that produced by bulbs grown in shade, is healthy in every other respect.

ACKNOWLEDGEMENTS.
Thanks are extended to Mr. Ernst van Jaarsveld for providing information, mainly in the form of photographs, featuring the micro and macro habitats occupied by Strumaria speciosa.

REFERENCES.
Craib C. The autecology of Strumaria speciosa on the Sonnenberg, south western Namibia. Herbertia Volume 60 2005 – 2006: 131 – 155.
Craib C. in Penrock Seeds and Plants Newsletter May and June 2008. Two rare Strumarias from south western Namibia and Nerine gibsonii from the north eastern Cape, South Africa. Web site address www.penroc.co.za, newsletter section.
Snijman D.A. Three new species and a new synonym in Strumaria (Amaryllidaceae: Amaryllideae) from Southern Africa. Bothalia 35.1: 21 – 27 (2005).

Strumaria speciosa flowers are borne on long pedicles. The petals start to reflex shortly after they open and this process is completed two or three days after the buds open. Throughout the flowering period the flowers remain spicily fragrant. In cultivation, however, only small pollen gathering wasps have been seen visiting the flowers, apparently attracted by a pollen source rather than the nectar.