published in "Cacti and other Succulents" (KUAS, German original title "Kakteen und andere Sukkulenten) 54 (1) 2003: III-IV

Ill. 1: close-up.

Ulrich Tränkle & Friederike Hübner

1. First description

Trichocaulon flavum N. E. Brown, J. Linn. Soc. 17: 165, t. 11. 1878

2. Synonyms

Trichocaulon karasmontanum Dinter, Repert. Spec. Nov. Regni Veg. 24: 16. 1927

3. Description

Plant: forming shrub of up to 30 by 50 cm, mostly smaller, branching at base. Stem green-gray, erect, up to 50 cm, 2 to 7 cm wide. Rows: between 18 to 31 ribs, each tubercle tipped with a pale to dark brown 4-6 mm long spine. Flowers: in groups of 1 up to 3 appearing predominantly in the upper half of the stem. Pedicel: between 0.5 to 1 mm long. Sepals: between 2.5 and 3 mm long, hairless, basis between 1 and 1.5 mm wide, acuminate, adjacent to the corolla .

Corolla: diameter between 1.1 and 1.3 cm, lobed to half-way down, glabrous on both sides, smooth outside, minutely papillate or smooth inside. Tube absent, flat or slightly saucer-shaped with small indentations around the staminal column. Colour greenish-yellow or  greenish-yellow with brown tips or even completely brown. Lobes ovate-deltoid, abruptly acuminate, spreading, spiky, 2.5-4 by 3.5-5 mm. Corona:yellow, rarely a translucent kind of brown. Outer Corona spreading, with 1.6-2.2 mm long spikes and separated into two delicate oblate horns below the middle, each of the horns tapering into outer horns. Inner corona 0.6-1 mm long, linear, obtuse, dorsiventrally flattened, incumbent on backs of anthers, shorter or longer than these, occasionally joining in the centre. Fruit: follicels, predominantly two, 75-180 mm long, 55 up to 105 seeds per horn.

Ill. 2: close-up.

Description according to Bruyns, P. V. (1993): A revision of Hoodia and Lavrania (Asclepiadaceae - Stapeliae). Bot. Jahrb. Syst. 115(2): 145‑270.

4. Distributional Range

Ranging from the eastern and southern slopes of the Namibian Great Karas Mountains, across the Cape Province, streching out East from the winter rainfall regions of Pella and Pofadder (the so-called Bushmanland) to Prince Albert and reaching close to Rietbron at the southern edge of the Great Karoo.

5. Cultivation

Hoodia flava prefers purely mineral, fluffy substratum, well permeable to water, and especially neutral or lightly acid substrates. Accumulated heat and full sunshine lead to rapid drying up and burn the shoot apexes. Impeded drainage and high humidity, especially in combination with temperatures below 10° to 15° should be avoided even though this species does not easily attract fungus rot.

New rooting requires a lot of patience and caution and should best be done in penumbra and in pure siliceous sand or Seramis adding water cautiously, but constantly. There is a high risk of decay. Overwintering is possible at a temperature of ± 10 °C – higher temperatures as for instance on the freely suspended shelf are also advantageous. Grafting has proved of value on Ceropegia woodi, resulting in a vigorously flowering plant. Reproduction is best accomplished by seed or grafting of scions.

6. Comments

H. flava remains relatively small over many years, yet it is an undemanding, all-season flowering plant. The species starts to flower at an age of 2 to 4 years. Although non-hybrid seed is still rather hard to obtain, the species has increasingly been granted admittance to collections over the recent years. It remains quite rare, however.

Hand pollination is successful with a little practice. Spontaneous seed buds have not been reported yet, neither have natural hybrids. Some very pretty hybrids have however been cultivated in collections.

Bruyn's revision of the species Hoodia and Varania (1993) moved H. flava from Trichocaulon to Hoodia sect. Trichocaulon.