Stapelia leendertziae N.E.Br.
Common names: bell stapelia, Leendertz’s carrion flower, carrion chalice, carrion flower, rugose cup starfish, maroon cup starfish, star flower, black bells (Eng.); aaskelk, aasklok, rooiaasblom, tulp assblom (Afr.)
Stapelia leendertziae is probably the most striking species of the genus Stapelia, especially when in flower, due to the unique, large, bell-shaped, deep reddish to dark purple flowers that are up to 12 cm long. It is widely grown in gardens but distinctly uncommon in the wild. The flower has a very strong and disagreeable, musty or carrion-like odour which attracts flies for pollination. The scent is, however, not overpowering and one really has to inhale deeply to smell them — from a few metres away, one hardly notices the aroma at all. This evergreen, relatively fast-growing species is easy to cultivate, relatively frost resistant and is an extremely low-maintenance garden subject.
Fig. 1. Stapelia leendertziae. A. Flowering plant of Stapelia leendertziae. (Photo Cameron McMaster) B. Bell-shaped, pendulous flowers with a smooth, shiny outer surface. (Photo Pieter Bester)
This plant is a perennial, clump-forming succulent, with stems 75–150 mm tall and 9–13 mm in diameter. The surface of the stem is velvety hairy, 4-angled and slightly concave between the toothed stem ridges. The tubercular stem teeth are each tipped with a rudimentary leaf that tends to drop off with age and are thus more distinct on young stems.
Fig. 2. Stapelia leendertziae. A. Square stems showing tubercles on the angles of the stem and rudimentary leaves. (Photo Pieter Bester) B. Trailing stems with pendulous flowers where the habitat allows for it. (Photo Retha van der Walt) C. Plant with an open flower and a fruit. (Photo Fritz Georg)
The striking but stinking flowers grow singly or in pairs, emerging from the mid-section of a stem, hanging down where space allows. Stems tend to branch near the point where a flower stalk is attached. The large a globe- to bell-shaped flowers are smooth and glossy on the outside and very finely hairy.
Fig. 3. Stapelia leendertziae flowers, in habitat. (Photos A & C Graham Grieve; B Marinda Koekemoer)
On the inside there are ridges that are brownish purple to maroon with a transversely wrinkled surface and long hairs that are more distinct towards the base of the flower. The corolla tube becomes 60–75 mm long, 50-100 wide at the mouth. The lobes of the corolla taper to acute pointed tips. The corolla is dark purple to maroon inside and paler outside; tube densely covered with purple hairs inside, outside glabrous with ± triangular lobes.There is a small outer and inner corona in the cup base of the corolla, both dark coloured and small lobed.
Fig. 4. Stapelia leendertziae. A. Corona lobes at the base of the corolla. (Photo SAPlants) B. Corona lobes in side view. (Photo Pieter Bester) C. Rugose inner surface of the corolla. (Photo Pieter Bester)
The fruit consists of a paired follicle (see Fig. 2), 115–150 × 12–17 mm, green and sometimes with paler green patches, with finely hairy surfaces. Flowering occurs in summer, from October to May, with a peak in November to January.
The plant is currently assessed as Least Concern (LC), but seeing that plants of the giant stapelia (S. gigantea) are traded for medicinal properties at markets, this species is also at risk because it is vegetatively very similar.
Fig. 5. Known herbarium records of Stapelia leendertziae at the National Herbarium in Pretoria (PRE).
Distribution and habitat
The rooiaasblom grows in grassland, in stony or rocky ground with shallow, sandy soils usually derived from sandstone and dolomite rock. It can also occur on rocky outcrops, often in the shade of trees and bushes, and in dry thicket. It has been recorded at altitudes of 450–1 626 m above sea level. It is endemic to southern Africa, occurring in Eswatini and South Africa, where it is found in the provinces of Gauteng, KwaZulu-Natal, Limpopo and Mpumalanga, and is patchily distributed in the mountains of the northeastern escarpment. Plants usually grow in large clumps, especially under the protection of larger woody trees. It is readily cultivated and can withstand a fair degree of frost.
Fig. 6. Stapelia leendertziae in habitat at Suikerbosrand, Heidelberg (Gauteng). (Photos Judd Kirkel-Welwitsch)
Derivation of name and historical aspects
The genus is named after the Dutch physician and editor of Theophrastus’s major works, Johannes Bodaeus von Stapel ( ± 1636). This species was named after Miss Reino Leendertz (1869–1965), later Mrs Pott, the first official botanist employed at the Transvaal Museum in 1898 and the first woman appointed as a civil servant in the then Transvaal. She was the first to collect this species near Heidelberg (Gauteng) in 1909. She made extensive herbarium collections in the northern provinces of South Africa.
Fig. 7. Illustration of Stapelia leendertziae by Cythna Letty, showing the corona lobes, re-produced from Flowering Plants of South Africa, plate 463. (©SANBI)
The dark maroon, bell-shaped flowers immediately distinguish the bell stapelia from any others in the genus. The stems are darker and dull green compared to those of S. gigantea and S. unicornis. Luckhoff described a form with a larger tube that is more inflated, giving it a spherical appearance, as a separate species, S. wilmaniae. Despite the various differences in the hairiness of the lower part of the corolla segments and inside of the corolla and corona structure, the latter is generally now accepted as synonymous to S. leendertziae.
Stapelia is naturally restricted to southern Africa and consists of about 30–40 species (depending on the classification followed). Other related, large or relatively large-flowered species include S. getliffei, S. gigantea, S. grandiflora, S. hirsuta, S. macowanii.
Fig. 8. Some large-flowered species related to Stapelia leendertziae. A. Stapelia gettliffei (Photo Pieter Bester), B. Stapelia unicornis (Photo Martin Heigan), C. Stapelia gigantea (Photo Geoff Nichols), D. Stapelia hirsuta subsp. tsomoensis (Photo Cameron McMaster), E. Stapelia macowanii (Photo Judd Kirkel-Welwitsch) and F Stapelia grandiflora (Photo Marinda Koekemoer).
Plants are pollinated by a variety of flies. They are tricked to such a degree by the colour, texture and scent of the flowers, which mimic that of decaying flesh, that many flies lay their eggs on the corolla of the flowers thinking it will provide food for the hatching larvae.
Fig. 9. Stapelia leendertziae. A. Close up of a flower showing the hairs and corona lobes inside. (Photo Alice Notten). B. Herbarium specimen of Stapelia leendertziae showing the inside of the corolla with fly eggs laid amongst the covering hairs. (Photo Pieter Bester)
The seeds are flat and have a tuft of hairs at one side. When the fruit (called a follicle) ripens, it bursts open, and as the moisture in the tuft of hairs dries out, the hairs expand to form a parachute-like structure and the seeds are easily carried off in the slightest breeze, to be distributed.
The leaves are minute and rudimentary, and are only really seen on the young growing tips and soon drop off. The green stems have taken over the function of photosynthesis.
The succulent nature of the plant aids in survival, especially in areas subject to frost. As long as the rooted portions are protected, usually when growing from cracks in rocks within their natural habitat, if the plant is damaged it can resprout from the pieces that survive.
Fig. 10. Stapelia leendertziae growing among rocks, in habitat. (Photo Ian Weideman)
This species is similar in the vegetative state to Stapelia gigantea, that overlaps in distribution with S. leendertziae, and is traded in traditional medicine markets. The latter species may also be collected and used in a similar way to S. gigantea.
Plants are frequently eaten by wild game and small mammals despite being very bitter to the human taste.
Other than being used in a similar way to S. gigantea and probably because this plant is so rare in its natural habitat, there is very little on record of the medical and cultural use of the plants except as a subject of cultivation in rockeries and gardens. It has been cultivated, both locally and abroad, since its discovery in the early 1900s – the original description was made from material cultivated in England. It is, however, rarely available in nurseries, except perhaps in specialist nurseries which trade in succulent or indigenous plants.
Stapelia leendertziae is a very hardy, evergreen, drought-resistant, sprawling succulent. It is an excellent succulent for a sunny rockery, but also makes an unusual container plant – shallow containers are most suitable to grow them in. Plant in sun or semi-shade in rich, porous, well-drained soil and water sparingly – when in doubt whether to water or not, don’t water. Stapelia leendertziae is an excellent subject for a water-wise garden. If grown in pots make sure they have good drainage, do not overwater and provide with bright light.
When in full flower, pollinators are attracted by the odour. For the eco-friendly gardener this is a way of attracting food for birds and reptiles such as lizards to the garden.
Fig. 11. Stapelia leendertziae growing in the Conservatory (display glasshouse), Kirstenbosch National Botanical Garden. (Photo Alice Notten)
Growing Stapelia leendertziae
Carrion flowers grow very easily in all parts of South Africa. Grow in direct sunlight throughout the year – this will encourage flowering. They will also grow in light shade or semi-shade in hot climates. The soil should be a well-drained, sandy medium consisting of equal parts of washed river sand, potting soil and topsoil and a pH of 6.5–7.5.
Provided that they are not over-watered and are given a warm position, your stapelia will flower successfully. When grown in containers, water from below. Too much water leads to rotting from the base and too little water causes the plants to shrink and die from the tips. Rather water plants sparingly than excessively. The plants require a period without water in winter (a dormant phase). They can survive long periods without water, but be sure to water them before they shrink too much as they will not be able to recover.
Grow plants in warm, dry places, if the temperature gets too low (below 15°C) or too moist, plants easily develop black spot and other fungal diseases. Fungicide is best applied during the dormant (winter) season as it may inhibit flowering and growth during the active season.
If needed, plants can be fed with liquid fertiliser during the active growing phase (spring and summer). Plants grow rapidly. When grown in containers and plants are crowding against the rims of containers, consider transplanting, but do this in spring just before active growth starts.
Propagation by seed is easy. Wait for fruit to ripen, at which time they will split to release the tufted seeds. Seeds stay viable for several months to a year or more if kept in cool and dry conditions. Sow seed in a well-drained, sandy medium, these will germinate within a week at 21°C.
Truncheons already with roots can be taken from large plants and planted directly into the garden. As plants form clumps that gradually expand, trimmed pieces can serve as a means to propagate more plants. Cuttings can be made with a clean, sharp knife, leave the cuttings for 4–5 days to allow the ends to air dry and then plant these in a well-drained, sandy medium. Leave these for 3–4 weeks without directly watering the severed ends to prevent rotting. When roots have been established, water sparingly.
Woolly aphids on the roots and underground stems and mealy bugs on the stems and bases are the most common problems. A strong jet of water or a 50:50 mix of methylated spirits and water can be used to eradicate these pests.
Black rot, a secondary infection after woolly aphid attacks, is also problematic. Remove all traces of black rot with a sterile knife, spray the plant with a fungicide such as Benlate (a.i. benomyl) and dust with flowers of sulphur. As soon as stem rot is noticed, the affected parts should immediately be cut away and destroyed.
See the Stapelia contribution in this series for further cultivation advice.
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Stoffel Petrus Bester
National Herbarium (PRE), Foundational Research and Services Division
Acknowledgements: the author acknowledges the following people or entities for making the use of their images available: Fritz Georg; Graham Grieve; Martin Heigan; Judd Kirkel-Welwitsch; Marinda Koekemoer; Cameron McMaster; Geoff Nichols; Alice Notten, SAPlants-Wikicommons; Retha van der Walt and Ian Weideman on iNaturalist.
Plant Type: Ground Cover, Succulent
SA Distribution: Gauteng, KwaZulu-Natal, Limpopo, Mpumalanga
Soil type: Sandy, Loam
Flowering season: Spring, Early Summer, Late Summer
Flower colour: Black, Red
Aspect: Full Sun, Morning Sun (Semi Shade), Afternoon Sun (Semi Shade)
Gardening skill: Easy