Asteraceae (Compositae) Archives

Othonna gymnodiscus

The photos in this post were originally published here as belonging to O. undulosa, but Derek Tribble of London kindly made me aware of them representing in fact O. gymnodiscus. For more information see Derek’s comment.

This is a tuberous, erect or sprawling plant to 35 cm tall, with leathery, oblanceolate to elliptic leaves which are tapering below and somewhat clasping.

The solitary yellow flowerheads are terminal or axillary and disciform ((without ray florets); they appear in July and August.

Its area of distribution is from Cedarberg to Worcester and Little Karoo to as far east as Port Elizabeth on sandy slopes and flats.

Othonna cacalioides (incl. O. minima, O. pygmaea)

Othonna cacalioides is a dwarf compact caudiciform with a flattened potato-like caudex, most of which is below ground. The plant body is broader than tall and to 10 cm across, covered by a tough leathery bark of a muted brownish or orangish colour.
The branches are reduced to low lumps with thickish, 2-2.5 cm long, and 0.8-1 cm wide leaves (only present in winter and spring).
From May to October, the plants produce inflorescences with 2-8 cm long stalks, each with up to six small, yellow flower heads.

Usually, the plants are found in shallow rock pans with a thin layer of coarse sand in sandstone pavements in the Northern and Western Cape (Bokkeveld Mountains to Gifberg). Sometimes they occur in patches of greyish moss. In both cases, they are often and hard to find, especially when not in leaf.
Although they are slow-growing and difficult to keep alive, this seems to make them only more attractive to collectors.

P.S.
In 2012 the Swedish botanist Bertil Nordenstam created a new genus (Crassothonna) with 13 species, formerly part of Othonna. One of these species (O. carnosa), for nomenclatural reasons, had to be renamed Crassothonna cacalioides. This has unfortunately created quite a bit of confusion because many people assume (understandably but wrongly) that this is the new name for Othonna cacalioides.

In short: Crassothonna cacalioides is what used to be called Othonna carnosa and Othonna cacalioides is still Othonna cacalioides.

Othonna intermedia

Of the about 100 species of Othonna, roughly a third qualify as succulents. Nine of these are deciduous geophytes (leafless during the resting period) and O. intermedia is a member of this group.

A resinous underground tuber produces a number of wedge-shaped, fleshy leaves up to 7 x 4 cm in size and green to blue-green or greyish in colour.
The yellow flower heads are 0.8-1 cm in diameter and appear between May and September (mostly in June and July).
Endemic to the Knersvlakte, where it occurs in quartz patches.

Senecio aloides (Grootdikblaar)

One can only wonder why De Candolle, who described this species in 1838, gave it this name, bearing in mind that aloides means “aloe-like”.
The plants form straggly shrubs of up to 70 cm tall, with few branches which are bright purple when young, becoming greyish brown with age. The cylindrical leaves are 3-7 cm long and 0.2-0.5 cm thick.

The species occurs on rocks and dunes near the coast from southern Namibia to the Cape Peninsula, where in July-October the plants are decorated with fragrant yellow flowerheads .

Curio sulcicalyx

This interesting little plant from southern Namibia and Namaqualand (as far south as Bitterfontein), comes under a variety of names: Senecio sulcicalyx, S. klinghardtianus, S. iosensis, Othonna/Senecio/Kleinia pusilla (pusillus).
It has a preference for rock crevices.

A great part of the plant is underground with rhizomes and tuberous roots.
The branches are up to 5 cm long. The leaves are 1 -2.5 cm long and 0.7-1.2 cm wide, sometimes shortly hairy.
Although the flower heads are usually white to mauve, in certain forms they are yellow; they appear from February to July.

Curio (Senecio) citriformis

This species was described in 1956 from material collected at Donkerkloof northwest of Montagu. For whatever reason, modern references place the plants at least a hundred kms to the East in the Little Karoo, either at the foothills of the Klein Swartberge or between Barrydale and Ladismith. *
They are found on rocky flats and outcrops.

Their 5-10 cm long fleshy rootstocks branch at soil level or below and thereby form small cushions.
The leaves are up to 3 cm long and about 1 cm thick and wide, spindle-shaped or almost spherical with tapered ends like a lemon (hence the name). They have a bluish grey waxy cover and are decorated with around 40 longitudinal clear stripes.
The 10-15 cm tall peduncles bear 1-3 creamy white flowerheads about 0.5 cm in diameter and appear in Jan. – March.

*All pictures apart from the first one, were taken a week ago about a km northeast of Montagu.

Senecio crassissimus

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)

Othonna protecta

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.

Othonna carnosa

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.
Pictures are usually easier to understand: the flower heads of the first species below (Othonna euphorbioides) are disciform; the ones of O. carnosa are 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.

Othonna taraxacoides

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.