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
No less than 25 synoniems have been recorded for this species, so it will come as no surprise that it is quite variable.
As a rule, the plants consist of only one pair of leaves, rarely 2 or 3. These leaf-pairs are 20-50 mm long and 15-30 mm wide, sunken into the ground. Old leaves stay on the plants for 1 or 2 years.
The flowers appear in April – June; they are 20-50 mm in diameter and may be white, pink, red , magenta, or yellow (see part 2). Even within one population one can come across all these colours.
The plants are locally abundant on flats or slopes rich in quartz pebbles in the Vanrhynsdorp area.
The first 3 pictures were taken on 30 March 2012, # 4 early next morning. Last one: 3 Sept. 2010
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).
Old plants of this species form clumps with up to 20 egg-shaped (=oviform) bodies, which are 1-2 cm tall and 1-3 cm in diameter.
Especially when flowering, the very dense stands in which they grow present an unbelievable show. The white to rose-pink flowers appear in August-September.
The plants occur on quartzitic flats and slopes in the southern Knersvlakte, where the rainfall is on average about 125 mm per year (mainly in winter).
Attractive dwarf shrublets up to 15 cm tall with a caudiciform base up to 3.5 cm in diameter.
Branches are short and fat, with peeling yellow-brown bark; covered with flat white phyllopodia (leaf-bases) when young. The leaves are usually up to 4 cm long and 5-7 mm wide.
The flowers are tubular, erectly spreading to pendulous and relatively large (up to 1.8 cm long). They appear in November and December.
This species is widely distributed from southwest Namibia to the Knersvlakte, on flats and stony slopes, often with quartz rocks or pebbles.
Rainfall in the area is 100-200 mm per year, mainly in winter. The temperatures are high in summer and moderate in winter, sometimes with light frost.
In my preceding post (https://enjoysucculents.wordpress.com/2015/11/01/conophytum-khamiesbergense/) I asked the readers’ opinion on the slide scans used there.
A big thank you to all who were kind enough to respond to that request (and I’m quite chuffed because all responses were positive). Being able to mix pictures that were taken digitally with ones that were scanned, gives me a lot more options for posts.
Today’s subject with its bizarre finger-and-thumb-like leaves is certainly one of the more peculiar succulents. One cannot help but feeling that some of this otherness is reflected in its taxonomic history:
The taxon* was described in 1789 as a Mesembryanthemum, in 1925 it was placed in a genus of its own (Dactylopsis) and in 1995 it was incorporated in Phyllobolus (only to be returned to Dactylopsis in 2006). In 2013 it was reinstated -together with many other species- as a member of Mesembryanthemum.
* Taxon is a term to refer to a taxonomic group or unit of any rank (a family, a variety or whatever -depending on the context).
The plants form clumps 10-20 cm tall and are heteromorphous (of variable shape): the first leaf of a growing period is long and the second short, giving the appearance of a “finger and thumb”.
They flower at the beginning of the resting period (November-December); the flowers stay open day and night for 3 weeks or even longer.
To see the plants in the wild, you have to go to the Vredendal/Vanrhynsdorp area of the Knersvlakte in Namaqualand, where they occur on shale covered with quartz pebbles.