Ceropegia crassifolia var. crassifolia
Ceropegia crassifolia Schltr. var. crassifolia
Common names: leathery-leaved ceropegia
Members of the genus Ceropegia in the strict sense, are characterized by tubular flowers specially adapted for the temporary capture of insects for pollination purposes. The variety of structures and hairs, the coloration and the pollination strategies, make this a fascinating group of plants. In the narrow sense there are about 180 species in Ceropegia. With the recent inclusion of the stapeliads and Brachystelma by Bruyns in 2017, the genus now almost comprise a 1 000 taxa.
Figure 1. Inflorescence and leaves of Ceropegia crassifolia var. crassifolia.
Ceropegia crassifolia var. crassifolia is one of the larger-flowered southern African ceropegias and because of its variable morphology, coloration of flowers, being a quick grower, and suitable for a range of cultivation positions (directly in the garden, hanging baskets or pots), it could almost be cultivated anywhere.
Plants are perennial, resprouting annually from its underground rooting system and somewhat succulent. The fleshy, fusiform roots are arranged in a cluster from where the erect, creeping or climbing stem originates (in most cases climbing into bushes). The fleshy stems are up to 10 mm thick and can become up to 2 m long and are ribbed lengthwise. When broken, it exudes a clear sap. The leaves are broadly elliptic to lanceolate, 30–80(–100) × 5–45 mm, decreasing from the base to the tips, leathery; the margins flat or wavy, hairless or roughly hairy.
Figure 2. Ceropegia crassifolia var. crassifolia. A: in habitat, just re-sprouting after it died back the previous winter – note the wavy leaf margins, the climbing/twining growth-tip and leaves reduced towards the tip of the stem. B: opposite leaves with very short petiole. C: clear sap. D: thick, leathery and succulent leaves. E: large leaves with entire margin.
Flowers are carried in an inflorescence with peduncle 3–30 mm long, each contains 3–10 flowers. The individual flowers open successively and are 25–50 mm long. The ± top third is divided in segments, with the bottom two-thirds being a tube. The tube is slightly bent at the base containing a distinct basal globose inflation. The lobes are erect, 9–13 × 3.0–4.5 mm; with the tips fused to form a fleshy cage over the mouth of the tube. The lobes are not twisted in the bud, and their margins are strongly rolled under, and keeled on inner surface.
Figure 3. External parts of the flower of Ceropegia crassifolia var. crassifolia.
Figure 4. Segments of the corolla tube of Ceropegia crassifolia var. crassifolia. A: viewed from outside with the left segment removed. B: dissected shown from the inside. C: sinus showing hairs that move in the slightest breeze – assumed to attract possible pollinators.
Figure 5. Parts of the tube of Ceropegia crassifolia var. crassifolia. A: globose base viewed from the outside. B: dissected globose base viewed from the inside. C: Shaft of the tube showing the white/maroon longitudinal tripes and downwards-pointing hairs on the inside surface.
The flowers are usually pale green to cream-coloured with purple to maroon markings and blotches on the outside and pink to maroon stripes on the inside. Long purple or white hairs are at the sinus of the lobes of the segments. The male and female parts of the flower are fused together into a structure called the gynostegium which contain the pollen that are aggregated in structures called pollinaria. Two pollinia are fused together by a clip which is utilized to adhere to a part of a pollinating insect and is removed as this unit.
Figure 6. The gynostegium of Ceropegia crassifolia var. crassifolia. A: side-view – note the erect white and maroon structures known as the corona lobes. B: angled view showing the inner and outer corona lobes. C: side view in close-up – note the yellow patches which are the pollen gathered together in sacs as a unit (pollinia).
The fruits are succulent follicles 70–100 × 3–4 mm and carry the seeds. The seeds are ± ovate and contain a tuft of white hairs on the one side.
Ceropegia crassifolia is very variable in morphology and colour, even in the same population. It flowers in summer, from December to February, but flowers are also recorded in spring (August) and autumn (April).
This species is assessed as Least Concern (LC). (Foden & Potter 2005).
Distribution and habitat
In South Africa it is found in scrub and bushveld in the Eastern Cape, Gauteng, KwaZulu-Natal, Limpopo, Mpumalanga and North West Provinces, but it is not endemic to South Africa. It is further also widely distributed in Namibia, Kenya, Botswana, Zimbabwe and Swaziland.
Figure 7. Distribution of Ceropegia crassifolia var. crassifolia based on records at the National Herbarium (PRE) in Pretoria.
Derivation of name and historical aspects
The genus name Ceropegia is derived from the Greek words keros, which means ‘wax’, and pege, which means ‘streams’ or ‘fountains’, alluding to the fact that many species have waxy flowers with long tubes. The epithet crassifolia is derived from the Latin words crassus and folia that means ‘thick-leaved’ and is in reference to the thick leathery and fleshy leaves very distinct in this species.
Figure 8. Close-up of the inflorescence with buds and one open flower of Ceropegia crassifolia var. crassifolia.
The first specimen in South Africa was collected by T.R. Sim near King Williams Town, in 1893 and described by Rudolph Schlechter. The leather-leaved Ceropegia falls in a group of other climbing Ceropegia with fusiform roots. The other variety, Ceropegia crassifolia var. copleyae (Bruce & Bally) H.Huber, is endemic to Kenya. The 2 varieties are distinguished based on the smaller flowers (tube less than 10 mm long, with lobes 3–4 mm long) in var. copleyae and the flowers much larger (tube 15–32 mm long, lobes 5–12 mm long) in var. crassifolia. It is said to be closely related to Ceropegia nilotica and C. stenantha.
Figure 9. Tubular flowers with canopy (open or closed), typical of most Ceropegia species. A: Ceropegia conrathii. B: Ceropegia meyeri. C: Ceropegia stapeliiformis subsp. stapeliiformis.
Flies generally pollinate ceropegias. The special tubular structure of the flowers is specifically adapted to capture the pollinators temporarily. In most species of Ceropegia the possible pollinators (insects) are attracted from a distance by the scent of the nectar. Sometimes the scent is sweet, but mostly foul-smelling. In many members of the genus in southern Africa, though, the scent is hardly discernable by the human nose. On the inside of the tube (especially at the mouth before the basal inflation) hairs are found, all of them directed downwards. When a pollinator enters the cage and moves down the tube, the stiff hairs makes it difficult, if not impossible, to move out again. The insect is thus almost forced to move further down where a very speciaIized structure containing the pollen mass is housed. In the flower, pollen sacks become attached to the bodies of the pollinators. After about 4 days, the flowers start to wilt. When this happens, the hairs become lax and the pollinator can leave its cage, pollination taking place when it enters another flower.
Figure 10. Single flower of Ceropegia crassifolia var. crassifolia in side view.
The aerial stems die back in winter but re-sprout annually. This is a mechanism to overcome the unfavourably time of year and the plant rest is thus protected against low temperatures.
The few follicles that form, are evidence of the specialized pollination strategy. Each follicle, however, produces a large amount of seed. The seeds are mainly wind-distributed and are dispersed by floating on the gentlest breeze, with their parachute-like tufts of white hairs.
This species, like most ceropegias, is widespread, but with low population densities.
Very little information is known on the natural use of this species by indigenous people. Many other members of this genus, however, produce tubers that are edible and used as a survival food.
Ceropegia crassifolia and various other species of Ceropegia are eaten as a vegetable, presumably cooked as spinach.
This species is mainly a collectable and grown as a container plant.
Figure 11. Seedlings of Ceropegia crassifolia var. crassifolia, germinating between 10–18 days after being sown.
Growing Ceropegia crassifolia var. crassifolia
Ceropegia crassifolia is best used as a container plant under roofed patios or lapas, on verandas, balconies of flats, or any other place in and around the house where space is restricted. Like most indigenous species, except C. woodii, C. crassifolia is not generally available at nurseries. It is produced mainly by collectors of these novelty species and is available from a few nurseries specializing in succulent or indigenous plants.
In its natural environment, root development is stimulated when the nodes touch the soil. The plant is thus easily grown from cuttings. Make sure the cutting contains a few nodes, let it dry out for a few days, after which it can be planted. Success of rooting can be much improved by dusting the severed end and a bit more of the stem with a commercial herbaceous hormone powder that will stimulate quick rooting. If available, plants can also be easily grown from seed. Sow seed as fresh as possible, but preferably in springtime or early summer. Make sure that the seeding medium is well drained and keep the seed wet until they germinate after about ten to eighteen days. Be sure to treat the seedlings for damping off and fungal infections.
A light sandy soil with a little compost and good drainage will give satisfactory results in growing the plant. Take care not to be too lavish with artificial fertilizers and water plants sparingly. It naturally occurs mainly in summer-rainfall areas, so be sure to give it a resting period by withholding water in winter.
As with most stapeliads, ceropegias are also prone to infestation by mealy bugs, woolly aphids and red spider. Woolly aphids usually attack the roots and this causes secondary infection by a fungus (black) rot that may easily destroy plants. Environmentally friendly or chemical treatments for all these diseases are described and listed in the Kirstenbosch Gardening Series on growing succulents.
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Pretoria National Herbarium
Plant Type: Climber, Scrambler, Succulent
SA Distribution: Eastern Cape, Gauteng, KwaZulu-Natal, Limpopo, Mpumalanga, North West
Soil type: Sandy, Loam
Flowering season: Early Summer, Late Summer
Flower colour: Brown, Purple, Cream
Aspect: Full Sun, Morning Sun (Semi Shade), Afternoon Sun (Semi Shade)
Gardening skill: Easy