Monadenium belongs in the Euphorbiaceae family, which contains about 320 genera and over 8000 species of geographically widespread plants, which range from annual herbs to large trees. This genus Monadenium has 50 known species, 46 of which are confined to tropical East Africa. Its eastern distribution line is the Indian Ocean. This genus does not exist in Madagascar. Throughout its area of distribution endemic species, varieties and forms of monadenium are numerous, with their habitat often being restricted to a singular hilltop. This high rate of endemism suggests a recent origin and/or a strict response to its environment, which sets limits on the expansion of distribution.

All Euphorbiaceae have a milky sap that may be harmful to the touch. The inflorescence has a complicated structure, based on the cyathium, which consists of an involucre containing one reduced female flower and several male flowers. There are protective bracts and nectarines. The fruit is a capsule, which explodes on reaching maturity.

The word "Monadenium" is derived from Greek, meaning "Single Gland".  F. Pax originated the name in 1895 based on the initial species of the genus to be described, Monadenium coccineum. This distinguishing characteristic for which the name was applied emanates from the flower structure. Flowers consist of a cup-like bracteate head, truncate at the top, open at one side or below the middle with a "single gland" of varying width on its top margin. Each has an interior series of 5 membranous lobes. Bracts persistent similar to its closest cousin Euphorbia with either gaping or overlapping margins.

Many forms occur within the genus from the diminutive terrestrial to an 18-foot arborescent variety. All known species of Monadenium are perennials, which always possess tuberous perennial roots and annual herbaceous growth. The bulk of these are what is termed geophytes, plants adapted to specific climate and ecological conditions, which include extended periods of drought. Many Monadenium have comparatively large rootstocks and a minimum of organs necessary for reproduction so that minimum energy is wasted on developing stems above the ground.

Although the genus is remarkably free from disease and insects it is susceptible to rot when exposed to moisture in the winter. The genus across the board is a winter dormant plant and as such must be kept absolutely dry during this period.

All species of monadenium contain copious latex composed of resins, mueilage and euphorbic acid in varying proportions. Some are highly irritating to the skin. None of the species have been determined to have any commercial value although some of the spineless variety are browsed upon by game animals and indigenous cattle.

Culture of the genus varies between species but the general rules of succulents apply with this genus. Well drained soil is always required, water only when in leaf and feed with low nitrogen fertilizer during the growing period. Exposure to sunlight varies depending on the species/variety. The plant should be shaded if signs of sunburn occur. Typically the anthocyanins (the red pigments) will present themselves when given too much sun, hence the opposite with a well shaded plant, the chlorophylls will become prominent when more shade is given. It’s always a battle to find a happy medium.

There are too many species to talk about them individually so I encourage anyone with uncommon and/or exotic specimens to bring them to the October meeting. I will be bringing approximately twenty plants for display.

Literature cited: Peter Bally, The Genus Monadenium 1961