Namibia Archives - Page 3 of 4

Hoodia (Trichocaulon) alstonii

Of the small-flowered Hoodias this is by far the tallest, with plants growing into many-stemmed shrubs up to slightly over a meter tall and 0.5 m wide.
The stems have an unusual whitish, grey-green colour and their 20-22 obtuse angles are armed with exceptionally hard and sharp spines.
The upper parts of the stems produce large numbers of flowers 1-1.8 cm in diameter.
The species has an unusual distribution. It occurs in the winter rainfall area of
Namibia on stony hillsides east of Luederitz and along the lower reaches of the Orange River.
In South Africa it also occurs along the lower Orange River: the western part of the area here receives rainfall in winter, whereas in the eastern part the rain falls in summer.
These habitats are surprisingly arid and in general the plants grow in the open on either rocky slopes or stony, flat areas.

Crassula columnaris (part 3 of 3)

And here some pictures of subsp. prolifera.

Crassula columnaris (part 2 of 3)

More pictures of subsp. columnaris.

Crassula columnaris (part 1 of 3)

It takes plants of this species 5-10 years to reach maturity and become columnar.
There are 2 subspecies, each with a number of local forms.
The plants are often locally abundant on gentle slopes and in depressions (often with quartz gravel); sometimes they also occur in shallow soil on rocky outcrops.
The flowers are white, pale yellow (often tinged red) or rarely almost red.

Subsp. columnaris is usually unbranched, with columns 2-3.5 cm wide, often as long as broad.
The inflorescence is swollen, rounded to flat and appears from May to September
The plants are monocarpic, which is another way of saying they die after flowering.
They are found in most parts of the little Karoo, the adjoining western Great Karoo and towards Calvinia.
Subsp. prolifera reaches a height of 3-10 cm when in flower and forms several short branches at the base. Often these branches easily break off and take root.
The inflorescence is more or less branched and appears from July to October. After flowering, the plants often regenerate from the lower branches.
This subspecies occurs in most parts of Namaqualand and adjoining areas of Bushmanland and southwestern Namibia.

The four pictures all show ssp. columnaris.

Avonia papyracea (part 2 of 2)

These pictures show subspecies namaensis.

Avonia papyracea (part 1 of 2)

Even if one has no knowledge of Latin, it is probably easy to understand that papyracea means papery. This refers to the thin, white scales that cover the stems.
These scales are in fact modified stipules: outgrowths of the base of the leaf stalk. By reflecting and diffusing light, they act as sunshades. This effect, combined with controlled aeration*, reduces evaporation. The scales are also able to trap dew.
*It has been noted that in hot, dry conditions the scales tightly overlap each other like roof tiles, whereas in cooler and therefore damper weather they can open out to some extent so that the leaves are more exposed.
As Gordon Rowley in “Anacampseros, Avonia, Grahamia” (1995) remarks, it seems surprising that such an efficient adaptation has, apparently, evolved only once.

The scales are about 5 mm long and wide and hide the minute leaves.
The stems are usually about 5-8 cm long and 0.7-1 cm thick, arising from a thickened tuber. As in other Avonia species, the stems that carry flower buds grow more or less horizontal, but become erect on the day of flowering and stay that way until the seeds have been dispersed.
The scented flowers are creamy white and appear in late spring and early summer.
There are two subspecies: subsp. papyracea occurs throughout the Little Karoo and is also found in the Great Karoo, whereas subsp. namaensis occurs in southern Namibia, the Richtersveld and Bushmanland. Both subspecies seem to feel most at home amongst white quartz pebbles.
According to the literature the main difference between the two is that in the first one, the edges of the scales are entire (without any teeth or other incisions) and in the second one saw-edged to toothed.
The following pictures show plants of subsp. papyracea.

Senecio cotyledonis (2)

The companion plant in the last picture is Adromischus triflorus

Senecio cotyledonis (1)

When the Swiss botanist Augustin de Candolle described this species in 1838, he apparently saw a likeness to a Cotyledon. But when I ran through the mental pictures of Cotyledons that I know, I wondered what resemblance he could have had in mind. So, some detective work was called for.
Did de Candolle compare his new species to a plant that at that moment was incorporated in Cotyledon, but now belongs in another genus? That is certainly a possibility, as no less than 471 plant names have been associated with the genus at some stage.
On the other hand, looking through “Cotyledon and Tylecodon” by Van Jaarsveld and Koutnik, it struck me that some narrow-leaved forms of C. orbiculata could well have been the inspiration for de Candolle’s name. Let’s not forget that he probably knew many plants from descriptions or at best from black and white drawings, rather than from live material. In the book I just mentioned, there are a few reproduction of old illustrations. One dates back to 1701 and represents Cotyledon africana frutescens, folio longo & angusto…. ( the shrubby Cotyledon from Africa, with long, narrow leaves), which is now known as C. orbiculata var. spuria. This picture may well have spurred (pun intended) the author to use his epithet.

Well, enough of historical speculation, let’s move to present-day reality.
S. cotyledonis is a shrub of up to 1 m tall, with thickish stems and succulent triangular to almost round leaves up to 5 cm long and about 3 mm wide. The leaves give off an unpleasant smell when damaged, which is why it is called stinkbos in Afrikaans.
The plants flower in spring. They are widespread from Namibia to the eastern part of the Little Karoo. Usually they are found on dry stony slopes, but sometimes they are abundant in clayey soils.

To be continued.

Monsonia (Sarcocaulon) crassicaulis, part 1

Together with M. salmoniflora this is the most common succulent Monsonia. The plants are widely distributed in the southwestern part of Namibia and the winter rainfall area of South Africa. They grow here mainly in winter from May to July and flower mostly from August to early November. The species also occurs in the summer rainfall regions of Bushmanland and the Great Karoo, where they are dormant from May to August and grow in spring and autumn. Not surprisingly one can also find them in the transitional zones between the summer and winter rainfall areas.

monscras 1627

monscrasDSC_4154

monscrasDSC_4156

To be continued.

Adromischus filicaulis (part 1: ssp. filicaulis)

Adromischus filicaulis is widespread (occurring from Namibia to Uniondale) and often common. It is also extremely variable.
The subspecies filicaulis is found from southern Namibia to east of Vanrhynsdorp; it most often grows on rocky outcrops and gravelly slopes and usually has erect stems.