The giant carrion flower is only one of a large variety of carrion flower species, or Stapeliads. It grows in Southern Africa. It has the largest flowers in the group - up to 40 cm (16") in diameter; this also makes it the largest flowered succulent plant species in the world. It is very typical of the group in that these flowers emit a foul odour reminiscent of rotting meat, and thereby attract flies and bluebottles. These insects are not eaten - as some people mistakenly assume - but are merely used as pollinators.

Scientific Name

This species was named and described by NE Brown in 1877. The genus name Stapelia was created by the great Swedish naturalist Carl von Linné, or Linnaeus, in 1737, after the Dutchman Johannes Bodaeus À Stapel, who had found related species in the old Cape Colony. The species name, gigantea, simply means 'gigantic' and refers to the flowers rather than the plant itself.

Appearance

Stems

This carrion flower can be easily recognised as being a member of the group, even when not in bloom. The above-ground portions of the plant consist of a number of fairly short, succulent, finger-like stems. These stems are four-angled, with a ridge or 'wing' on each angle with hollows or grooves between the wings. There are regularly-spaced 'teeth' or tubercles along the ridges forming each angle. Occasionally stems form that are five- or even six-angled.

The stems are succulent and soft, with a somewhat velvety texture from short 'hairs' all over it. The leaves are reduced to soft and dry papery remnants only about a millimetre in length, at the tips of the tubercles, and have lost their function of producing food for the plant.

The stems themselves now carry out this process, called photosynthesis. They become green in spring and summer when supplied with adequate water, but in autumn and winter, or during long dry spells, they become brownish, reddish or purplish. These pigments protect the plants against harsh sunlight and against drying out.

The finger-like stems are usually about 2.5 cm (1") in thickness. They usually branch at ground level, with the tips of the stems curving upwards, forming clumps reaching a metre in width, with the erect tips of the stems reaching 30 cm (12") in height under optimal conditions. Plants growing in harsh circumstances can be much smaller, with the stems less than 1.2 cm (1/2") thick and only about 10 cm (4") tall.

Branching at ground level, the stems root wherever they touch the ground, and in this way the plant clumps can grow and spread outwards. Sometimes the inner portions die off, leaving a number of unconnected clumps of plants. The root system is quite shallow, and the plants grow best in loose soil. They are prone to rotting in soils that are too moist.

Indeed, the succulence of these plants is an adaptation to fairly dry conditions. The stems store water, 'filling out' after adequate rains and then storing this water for use during drier periods. Because, compared to leaves, the stems have less of a surface area in relation to their volume, water evaporates from them much more slowly than it would from large, flat leaves.

A strange form of growth that often occurs in cultivation is called a 'crest'. It results from overactive branching at the growing tips of the stems, causing the plant to develop as a convoluted mass rather than as tufts of finger-like stems.

Flowers

The flowers are of course the surest giveaway. They appear in the spring or summer. The flower 'buds' are already very distinctive: large and inflated like a bladder, with the petals all joined together and extended forward into a lengthened, spirally twisted tip. The outside of the petals are greenish to pinkish, with longitudinal ridges stretching along their backs towards the tips.

The bud opens to unveil the interior of the flower in all its glory. The flower is starfish-shaped with five petals (occasionally six or even more), the tips of which are long and thin. The upper surface of the flower is covered with thin squiggly ridges and short hairs. The hairs are reddish to purplish and increase in length and density towards the centre of the flower.

The background colour of the flower ranges from pale yellowish, even almost cream, to brownish or reddish. The squiggly ridges are darker in colour, reddish to purplish. Towards the centre of the flower they join up into concentric rings.

In the centre of the flower is the structure known as the 'corona', or gynostegium. This is like a little flower in the middle of the big flower. The corona structure varies enormously between different carrion flower species, and there even exists a lot of variation within each species. In the giant carrion flower, the corona is about 12-20 mm tall, 13-15 mm broad, and dark purple.

The corona holds the pollen-packs of the flower, as well as the ovaries where the seeds develop. The pollen-packs, or pollinaria, are designed to snag on the leg or mouthparts of a fly that penetrates to the centre of the flower. The pollinarium clings to the foot and is pulled out; when the fly next alights on another flower and goes to its centre, the pollinarium (if all goes well) now gets jammed into a groove called a 'guide rail' and the pollen bags 'snap' off and remain behind while the fly flies away.

From here a pollen tube grows into the gynostegium and the pollen grains are released into the ovaries. And so the flowers are pollinated.

The flies and other pollinators are attracted by the strong odour of the flowers. The odour, along with the fleshy colour and appearance of the flower, and its hairiness, fools the flies into thinking it is a rotting animal carcass. From all over they fly in to investigate. Many times they even lay eggs on the flowers; such clumps of eggs can often be seen amidst the hairs. Larvae sometimes hatch from these eggs, but finding no food, they soon die.

Seed Pods and Seeds

The seed pods, also called follicles, of carrion flowers are very distinctive in appearance. They generally grow in pairs, united at the base, but with the two ends standing apart at an angle with each other. In the Afrikaans language of South Africa these follicles are called 'Bokhorings' (goat's horns) for their similarity to the horns of an ungulate.

Inside the follicles, the seeds are tightly packed and very neatly arranged. When ripe, each follicle splits open along a suture that runs its entire inner or upper length, releasing the seeds. The seeds are small and flat. On the one end they carry a white, downy tuft of hairs. The hairs lie closely pressed together in the follicle but when the follicle opens the hairs spread out into a little 'parachute' that helps the seed get carried away by the wind.

The seeds detach easily from the downy tuft, and so they can drop off and land on the soil at any stage after being blown away by the wind. When they land in places with a bit of warmth and moisture and good, loose soil, they can germinate very rapidly.

Distribution and Habitat

The Giant Carrion Flower is one of the most widely distributed carrion flower species. It occurs in South Africa from the central parts of Kwazulu-Natal northwards to the Gauteng, Mpumalanga, Limpopo and Northwest Provinces. It is scattered throughout Zimbabwe and Mozambique, and also eastern Botswana. It has also been recorded in Zambia and Malawi.

Records of the species in Tanzania and Kenya are likely to be the result of plants that have 'escaped' from cultivation rather than being indigenous to the region.

These carrion flowers prefer bushveld or savannah regions where the winters are dry and not too cold. Here they often grow on flat ground with loam or stony soil. They frequently grow in light shade below trees or bushes, but also out in the open. They sometimes grow between rocks on hills or mountainsides. They are occasionally found in sandy soil close to the coast. Like some other stapeliad species they can often be found around villages; it seems that they take advantage of overgrazing by goats or cattle, managing to establish themselves where the cover of grass is broken.

Relationships and Similar Species

At their largest, the flowers of Stapelia gigantea separate it from all others. Flowers that are on the small side, can be distinguished from those of most similar species by the thin, tapering tips of the petals. The only exception is the closely related Stapelia unicornis. This species can be separated by its stems: they are light green in colour with much longer hairs than the stems of Stapelia gigantea. This species only occurs in central Kzazulu-Natal around the Tugela River.

Other closely related species are:

Gardening with Giant Carrion Flowers

It might be somewhat surprising that gardeners aren't put off by the smell of these flowers! In the warmer and drier parts of South Africa they are quite frequently planted, often in rock or succulent gardens where they fit in very well with a variety of other succulent South African plants. They work very well along with species of Euphorbia or Aloe, or with members of the Crassulaceae, the tackies. They can also be combined with other carrion flower species.

The smell is not as unpleasant as sometimes claimed, and can in fact become tolerable. At any rate if planted at some distance from the house it should be no problem... and might even draw the flies away!

The species can very easily be grown by means of either cuttings or seeds. Cuttings can be made at any time but work best in the spring or summer. The best way is to cut close to the base of an upright standing stem, close to where it branches. You can even cut off a piece that already has roots on it. At any rate this piece should now be kept to dry out in a cool and shady place. Dry it out for a week or two. Then root it in pure sand or a loose sandy soil mixture: either push it so the bottom 2-3 cm of it is in the soil; or lay it horizontally on the soil and put a stone on it to hold it down. Give it a bit of water every week or two - it should be moist but never wet. It should form roots in a month or two. It will then form new branches and develop into a new clump.

Seeds can be planted in a similar sandy mixture. What works very well is to insert them one by one into the soil with the 'round' end at the top and pushing the 'pointy' end (the end where the tuft of down-hairs attaches) down into the soil. Push them in until the top end is level with the soil. From here on keep them moist. Seeds need warmth to germinate well - but under optimal conditions they germinate profusely, with a rate of 80% or more. Don't plant the seeds too closely together so that they won't be too crowded. The seedlings will develop into pretty little plants in the first season and can be planted out the next.

In cold climates such as Europe or the USA the species would do best in hothouses or indoors in pots on sunny windowsills (for truly intrepid enthusiasts).

Giant stapeliads can be grown outside in gardens with the following provisions: first, the winter should not be too cold - preferably with no nights more than one or two degrees below freezing. Second, the winters should be dry, almost entirely rain-free. Third, even the summers must not be too wet. Ideally there should be stretches of at least a few consecutive dry, hot and sunny days during every month of the summer. Under wet conditions the plants will tend to rot. They can still be saved if the rotten parts are cut off and the remainders are dried out and re-rooted. A sunny position and well-draining soil will minimize the chance of carrion flowers rotting.

Aside from causing plants to rot, fungi can sometimes attack the stems and cause unsightly spots or blotches on the stems. These can be treated by spraying on a fungicide.

Scale bugs sometimes attack the stems, and mealy bugs sometimes infest the roots. These species can be controlled by insecticides.

On the whole, compared to other carrion flower species, the giant carrion flower is robust, resistant to diseases, and quick to recover.

This interesting plant can be quite handsome when well-grown, and a conversation-piece when in flower. It needs little water or care and is a very good choice for gardens in semi-arid tropical or subtropical regions. This species is among the easiest species of carrion flower to grow, and cultivating it can serve as a starting-point for getting to know the whole group! Successful cultivation of Stapelia gigantea could be followed by trying out other easy and attractive species like Orbea variegata or Huernia zebrina.

Further Reading

• Stapeliads of Southern Africa and Madagascar Volume 1 & 2, by Peter V Bruyns, Umdaus Press, South Africa, 2005