Crassula mesembrianthemopsis

Dinter

Family: Crassulaceae
Common names:
Foam flower Eng.

Crassula mesembrianthemopsis plants growing in quartzite soil

One of the smallest and most bizarre succulents in South Africa, this plant has seldom been seen in the wild and is virtually unknown in cultivation.

Description
Like all crassulas, this curious dwarf species is also a succulent, but adopts a curious survival strategy by submerging almost its entire body under the soil surface, leaving only its truncated leaf tips to protrude just above the soil surface. This is an excellent survival strategy. From the surface, the triangular leaf tips (about 5mm across) are arranged in a rosette with the whole plant not exceeding 6cm in diameter. Each leaf forms a long fleshy triangular cylinder, the longest outermost reaching up to 35-40 mm long, getting gradually shorter towards the centre of the plant. Unusually in the genus, the leaves are arranged spirally. Each arises from the corky succulent carrot-like taproot which can be 5-7 cm long. The leaves are grey green in colour with the leaf tips becoming completely grey making them very difficult to spot in the soil.

A white inflorescence, composed of many small flowers and not more the 3 cm high, appears as a dense cluster nested in the centre of the plant in autumn. The individual flowers are tubular with creamy white slightly recurved petals 5-7 mm long. Anthers are yellow. The inflorescence emits a pleasant fragrance at dusk. Tiny fruits form into capsules which release the minute dust-like seed which is dispersed by the wind and water.

Crassula mesembrianthemopsis infloresence

It is not known how long-lived these plants are in the wild but considering the relatively slow growth rate, estimates would be in the region of 2-4 years, perhaps longer if conditions are favourable.

Conservation status
Despite the apparent rarity of this plant, it currently has no threat status. This is a reflection not of its actual scarcity but rather its poorly documented distribution owing to its extreme inconspicuity.

Distribution and habitat
Crassula mesembrianthemopsis has seldom been seen in the wild and is only known from a few highly localised and disjunct populations stretching from Kenhardt in the Northern Cape of South Africa to the mouth of the Orange(Gariep) river and to the southern coastal parts of Namibia from Witzpüts to Cape Cross. The relatively large distribution range suggests that it is probably far more widespread than is thought. It thrives in fine white quartzitic gravel substrates where it is well camouflaged.

Derivation of name and historical aspects
The name Crassula literally means “little fat one”. The species name refers to its apparent similarity to plants of the Mesembryanthemum family.

Ecology
Soils covered with white quartizite pebbles are well known to harbour a vast array of dwarf succulent species, particularly in the winter rainfall parts of the western and northern Cape provinces and Namibia. This is due to the highly reflective properties of the quartz which keep soil temperatures cool during the hot summer months. The quartz also provides an ideal seed germination habitat. The seeds can germinate underneath the pebbles, which transmit enough light for photosynthesis, at the same time providing a cool environment protected from the elements. With time the plant will grow and push the pebbles to one side allowing it to reach the direct sunlight.

This species falls into a special group of South African succulents called “window plants”. They come from a variety of different plant families but have all convergently evolved into a similar morphology, adopting a similar photosynthesis and survival strategy. Such species include Haworthia truncata and other Haworthia species, Bulbine mesembryanthemoides, Frithia pulchra and Fenestraria rhopalophylla. Unlike most plants, these plants transmit light through the upper flattened tip of the leaf exposed to the sun, much like a window, allowing light to pass through the transparent leaf tissues. Photosynthesis takes place when the sunlight hits the lower internal leaf surface which is buried some centimeters below the ground. The purpose of this is to minimize the amount of leaf surface area exposed to the harsh elements.

Uses and cultural aspects
There are no known uses for this plant.

Growing Crassula mesembrianthemopsis

Crassulas are amongst the easiest plants to cultivate, however, this, species can prove difficult to grow. It is, however, easy to keep in cultivation once the right code has been cracked. The code is very well drained gritty soils with a low organic content. Good ventilation and bright light are essential. Being a dwarf novelty plant it is recommended that this species be cultivated in a pot rather than the open soil. A sunny windowsill should therefore work well. Water very sparsely and only when the plant becomes soft to the touch. Overwatering is the easiest way to kill this plant as the plants are very susceptible to fungal attacks which result in rotting. Feeding is not necessary and will only cause lush growth which will ruin the refined nature of the plant.

Propagation is easy from cuttings, especially leaf cuttings, at any time of the year which means they can be bulked up very easily. Remove the largest outermost leaves by pulling them away and to the side, tearing them gently away from the stem. Allow the leaves to stand for a few hours so the wound can dry and heal. Insert them into a dry gritty growing medium so that only the leaf tips protrude above the soil surface. Do not water the plants at this stage but rather keep them dry. Keep the pot in a bright situation out of direct sunlight where they will not get any water. After a week, they could receive a light sprinkling of water. Rooting should take place within 2 weeks. Once the leaf cuttings have visibly greened up, move them to a sunny spot, and before long young plantlets will develop into small rosettes.

If one could ever acquire seed, this could be sown in autumn. Mix the dust-like seed with a small quantity of fine sand. Spread the sand evenly over the surface of the soil which should be the same as the growing medium. Water immediately, preferably from below by standing the pot in a tray of water every few days. Keep the soil moist like this for the first month or so. Before long, tiny green plantlets should appear on the soil surface. Start to let the soil dry out between waterings. Soon the plants will bulk up and if one achieves the ideal growing conditions, one can raise many thousands of plants like this. The use of a damping-off fungicide is advisable.

The most susceptible time for these plants is in late autumn, where pots can sit wet for days on end. This is when plants are most likely to rot. Rather err on the side of caution and keep the plants too dry, rather than too wet.

References and further reading

  • Rowley, G. 2003. Crassula, A grower's guide. Cactus & Co. libri.
  • Tölken, H. R. 1985. Crassulaceae. Flora of Southern Africa. Vol. 14. Botanical Research Institute.

 

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Kirstenbosch Botanical Gardens
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This page forms part of the South African National Biodiversity Institute's plant information website www.plantzafrica.com.


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