Because of the peculiar orientation of its leaves, this species is often called Vertical Leaf Senecio or propeller plant.
The plants have creeping to erect stems, to 80 cm tall and much-branched.
The vertically flattened leaves* are variable in shape, size and colour, to 10 cm long, 3 cm wide and 3-5 mm thick.
Inflorescences are to a meter tall.
The species is widespread in central and southern Madagascar, where it grows on denuded granite rocks, often together with members of the Euphorbia milii groep, such as E. horombensis and E. fianarantsoae and Pachypodium species (first picture shows P. horombense in foreground).
* This vertical compression of the leaves is usually regarded as an adaptation which reduces the amount of light that reaches the leaf surface, resulting in lower daily water loss than in leaves in other orientations.
Pictures 3 and 4 show plants in cultivation (scans of old slides)
As the name implies, this species is often hiding under other plants or between rocks. For that reason, it is not easy to make good pictures of it. The photographer usually must choose between showing either what the plant looks like or how well it is hidden.
The plants are shrublets with fat (pachycaul) barrel-or flask-shaped stems and thin branches up to 30 cm long. They have soft leaves, which are mainly crowded at the branch tips and are long and narrow: 40-100 mm long and 2-3 mm wide.
The flowers appear from April to October.
One can come across these plant from central Namibia to the Little Karoo on gravelly flats and slopes.
Since its publication in 2000, “Cape plants” by J. Manning & P. Goldblattt has been one of my main sources of information on plants of southwestern South Africa. In 2012 a new edition was published, with the somewhat unwieldy title “Plants of the Greater Cape Floristic Region 1: The Core Cape Flora”. At the same time a companion volume appeared covering the flora of Namaqualand-southern Namibia and the western Karoo, called “Plants of the Greater Cape Floristic Region 2: The Extra Cape Flora”, edited by D. A. Snyman.
I acquired this set recently and am enjoying the great amount of new information.
One of the first things I did was looking at slides of plants I have not been able to identify yet and, as expected, this has already produced some ID’s. A peculiar thing I found out is that, where a species is mentioned in both volumes, the info is not always consistent. The subject of this blog is a case in point.
When identifying plants of the genus Othonna, one of the most important questions is whether the flower heads are disciform or radiate.
In the first case, all the little flowers in the flower head look more or less the same; in the second case, the flowers along the margin of the head resemble normal petals.
The visual information below is probably slightly easier to absorb:
the flower head on the left (Othonna filicaulis) is disciform; the one on the right (O. protecta) is radiate.
When I went through the text in my new acquisition, to see if I could identify the following pictures, I came across the name Othonna carnosa with the following info:
“Succulent shrublet with short, erect or sprawling branches, 10-30 cm. Leaves fleshy, ovoid to fusiform (egg- to spindle-shaped FN). Flower heads radiate, few in lax, terminal cymes on slender peduncles, yellow or white. Flowering mainly April-October. Sandstone slopes and stony flats. ”
Strangely enough, when I checked the description in Volume 2, some of the information appeared to be different: “Flower heads solitary , disciform , yellow.”
The first two pictures below were taken at the same place, with a few minutes in between. As you can see, in the first picture the flower heads are solitary, and in the second the peduncles are divided.
The disciform/radiate and yellow/white questions still remain to be answered, but I am now convinced that the following pictures show O. carnosa.
Almost two years ago I published a post on Othonna auriculifolia. Today’s subject could be considered the northern counterpart of that species. Both were described in the first half of the 19th century, when taxonomy was still a very European science. This probably explains why both specific epithets refer to well known European plants: taraxacoides means looking like a Taraxacum (dandelion) and auriculifolia means with leaves like Primula auricula (bear’s ears or cow slip).
O. taraxacoides is a stemless tuberous geophyte up to 10 cm tall. The leaves are leathery and wedge- to egg-shaped or more or less kidney-shaped. Usually they are 2-3 cm long and up to 2 cm wide, with small rounded teeth and often incised with 3-5 rounded lobes.
The flower heads are 0.8-1.5 cm in diameter and appear in July and August.
The plants occur on open pebbly places or quartz patches from the
Richtersveld to Kamieskroon.
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.
Polytomus means something like much divided and refers to the fact that the plants are much more branched than in otherwise similar species like S. scottii and S. odora.
In nature the plants form compact shrubs up to about a meter tall; in cultivation they may reach 3 m.
They are locally common in the Sanaag region of northern Somaliland in dry bush land on stony plains and slopes at altitudes between 1000 and 1900 m.
The flowers range in colour from white and yellow to pink, purple and magenta. They usually appear in October and November, but the accompanying pictures were made in late January.