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.
These pictures show subspecies namaensis.
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.
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.
To be continued.
This species is common in western Bushmanland. Photographed 2 Sept. 2010.
Pictures taken near Pofaddder, 3 Sept. 2010
At foot of Gamsberg, 4 Sept. 2010