Although the plants are very variable in almost all respects, they are always completely and densely covered with white to reddish hairs (except the inside of the flowers).
They have erect to creeping stems, 0.5-1.2 m tall and with egg-shaped to round leaves 16-40 cm long and 0.6-3 cm wide, often with an auriculate* base. The upper leaves are stalked, the ones near the base without stalks.
The inflorescenses are 15 cm wide and produce bulbils; the flowers have 1.4-3 cm long tubes and are red, pink, or yellow, often with red stripes.
The species occurs in central, eastern and northern Madagascar, usually on damp or wet rock surfaces.
Several varieties have been described, but they are not upheld in the Illustrated Handbook of Succulent Plants.
*auriculate: with small roundish or ear-like appendages.
Plants photographed in June 2017
When in flower the plants are usually 30-60 cm tall; they consist of one to a few rosettes.
The leaves are tightly packed but become more separated when flowering. They are 2-8 (sometimes 10) cm long and 1-2.5 cm wide, usually densely hairy and with longer hairs (cilia) at the margin.
The plants are found from southwest Namibia along the western coast of South Africa to the Cape Peninsula and the western Little Karoo to near Laingsburg. They often grow in coastal sands, but also on gravelly slopes and larger rocks.
Both the current and the old name refer to the white, bristle-like hairs covering leaves and branches in this species (hirtipes = with hairy stalks, hystrix = hedgehog).
The type plant was collected in the southern part of the distribution area, where some of the plants have almost hairless leaves. This probably explains the fact that the name hirtipes refers to the hairiness of the branches only. These branches are rather brittle and form tufts to 15 cm in diameter.
The leaves are lance- to egg-shaped, from round in cross-section to flat above and strongly convex below; they are 8-20 x 4-7 mm and usually as thick as wide.
The small tubular flowers are cream to yellow and appear from August to October.
Plants are found from Komaggas to near Vanrhynsdorp in habitats varying from gravelly slopes to loamy flats, often under rocks or bushes.
Plants of this species are sparingly to densely branched (usually from the base) and form clusters up to 9 cm in diameter.
The columnar plant bodies are usually erect (rarely more or less flat on the ground); 20-90 mm long and 6-15 mm thick.
Flowering occurs from May to October; the flask-shaped flowers have cream, 9-11 mm long petals.
The species is found in the western part of Namaqualand from near Port Nolloth to the Vanrhynsdorp area, on exposed quartz gravel flats and gentle slopes, rarely on rocky outcrops and in shallow pans on rocks.
The Latin word calculus means pebble and in this case probably refers to both the roundness and the firmness of the plant bodies.
These bodies are to 30 mm diameter, ball- to barrel-shaped, very firm, whitish-green to pale yellowish-green, without any markings; they form a hemisphere with age.
The flowers are open at night (sometimes staying open during cool mornings) and are said to smell strongly like cloves or carnations; they are golden yellow to deep reddish orange and appear in April-June.
The plants occur in full sun on salty quartz flats and gentle slopes in the Knersvlakte.
First picture taken 10th Sept. 2010; others 12th May 2017
This very variable taxon occurs from southern Namibia to the Cederberg in South Africa, but mainly in the mountainous area of Namaqualand near Vanrhynsdorp, in rock crevices or between boulders, often in very exposed positions.
The plants form much-branched shrublets up to 0,5 m tall. The leaves are green, sometimes turning yellowish green or purplish red; they are almost triangular in section, usually 20-35 mm long (sometimes as short as 10 mm or as long as 50 mm) and 2-4 (sometimes 6) mm wide, about as thick as they are wide.
In autumn/early winter (March-June) the flowers appear, which as a rule are yellow-green, rarely white with a pink tinge.
Four of the six species belonging to the section Columnares of Crassula are more or less well known (barklyi, congesta, pyramidalis and -of course- columnaris).
One other (C. multiceps) I have never even seen and the subject of this post is not widely known either.
It is a small, more or less erect plant, 8-25 cm tall when in flower, sometimes with several short branches at the base. The green to brown leaves are normally all about the same length (usually 5-8 mm but sometimes to 1.5 cm). They often covered with sand particles.
In September-November, the main stem bears many small rounded inflorescences on the upper part of the flower stalk.
The plants occur from Vanrhynsdorp to Calvinia, Worcester and Montagu on sandy or gravelly slopes (often facing south).