Stapelia

Stapelia is a genus of dwarf stem succulents, perennial herbs commonly known as African starfish flowers or in Afrikaans as aasblomme (carrion flowers), forming part of the Apocynaceae family.

The plants branch from the base in sympodial stems, while mostly not growing rhizomes underground. Sympodial stems are stems that form an apparent main stem when the original main stem-tip growth is repeatedly halted, replaced by new lateral growth continuing from successive secondary stems, imitating a simple stem. This brings about a lateral growth pattern in which the apical meristem is recurrently terminated and continued laterally, as if continuous but zigzagging.

Most stems are four- to six-angled and velvety from soft, short hairs, sometimes slightly tapering with tubercle-like teeth along the stem ridges or angles. The stem sides between the ridges are often compressed.

Small, fleshy and hairy leaves, often awl-shaped, grow along the stem ridges upon the tubercles. They appear insignificant but are enhanced by paired, stipular glands at the leaf bases. The leaves either drop off early or dry soon and persist.

The inflorescence is a hairy cyme comprising one to many flowers, usually growing from near a stem base. The mostly ill-smelling flowers, opening in sequence, have corollas varying from less than 1 cm to 40 cm in diameter. The flowers attract flies and blow flies as pollinators.

The corolla is usually deeply five-lobed, wheel-shaped, cup-shaped or funnel-shaped. The lobes sometimes have recurved tips, their upper surfaces often transversely wrinkled and hairy. Corolla colours vary among shades of yellow, brown red and purple.

There is an outer and inner corona in the corolla base, arising from the staminal column. The outer corona is wider and lower, five-lobed but each lobe sometimes forked. The inner corona is smaller and taller, its five lobes on the backs of the anthers, shorter than them or extended in horn-like protrusions that may have wings on the back or secondary horns.

The rectangular anthers have two locules, positioned horizontally upon the style head. Pollen-masses are attached within the anther cells.

The fruits are paired, spindle-shaped, erect follicles, more often hairy than not. Each seed is crowned with a hairy tuft or coma functional in wind dispersal.

During flowering earlier, pollination benefited from the absence of wind. Robust plants that cope with many eventualities also have their fastidious requirements where the procreative sequence can go wrong. Stapelias are rarely abundant in nature, popular in horticulture and easily grown from stem cuttings.

There were about 85 Stapelia species when White and Sloane published, 43 when Leistner published, 28 when Vlok and Schutte-Vlok published and 55 when Wikipedia was checked for this account written in 2021. All the species occur in Africa, most of them in southern Africa. Natural hybrids are common.

The plant in picture is Stapelia hirsuta (White and Sloane, 1937; Leistner, (Ed.), 2000; Vlok and Schutte-Vlok, 2015; Wikipedia; http://opus.sanbi.org).