Trichodiadema densum 

Trichodiadema densum is a low-growing succulent that is extremely reluctant to flower, but when it does, it has numerous bright pink daisy-like flowers in autumn.

Trichodiadema densum
Trichodiadema densum (Image: Wikimedia Commons)

Species Information

  • Scientific Name: Trichodiadema densum (Haw.) Schwantes
  • Synonym(s): Mesembryanthemum densum Haw.
  • Conservation Status: Least Concern (LC) according to Red List of South African Plants 2009, following IUCN Red List criteria.
  • Habitat: Rock crevices.
  • Key Uses: Ornamental.
  • Known hazards: None known.

Taxonomy

  • Class: Equisetopsida
  • Subclass: Magnoliidae
  • Superorder: Caryophyllanae
  • Order: Caryophyllales
  • Family: Aizoaceae
  • Genus: Trichodiadema

About this species

Trichodiadema densum is not a cactus but could be mistaken for one; its leaves are succulent and end in a circle of stiff hairs, giving the plant a similar appearance to some species in the cactus genus Mammillaria.

According to John Sims, who wrote the text accompanying the painting of this plant in Curtis’s Botanical Magazine, patience may be required when cultivating Trichodiadema densum. ‘This plant, though not of difficult cultivation, is extremely shy of flowering; so much so, that Mr Haworth…[from whom the specimen came]… informs us that it is one and twenty years since he has seen it in blossom.’

Geography & Distribution

Trichodiadema densum is found in the Cape Region of South Africa, from Uniondale to Willowmore and Great Karoo.

Description

Trichodiadema densum is a compact, mat-forming perennial short shrub, up to about 10 cm high, with woody stems and thick fleshy roots. The green succulent leaves (2 cm long) are each tipped with a crown of white hairs. The daisy-like flowers are vivid carmine pink 4–5 cm in diameter, opening in the morning and closing later in the day. The flowers appear from autumn through to spring.

Illustration from Curtis's Botanical Magazine

Trichodiadema densum illustration


Hand-coloured engraving of Trichodiadema densum (as Mesembryanthemum densum) by Sydenham Edwards (1809), taken from Curtis’s Botanical Magazine (Image: RBG Kew)

Curtis’s Botanical Magazine (Editor: Martyn Rix) provides an international forum of particular interest to botanists and horticulturists, plant ecologists and those with a special interest in botanical illustration.

Now well over two hundred years old, the Magazine is the longest running botanical periodical featuring colour illustrations of plants. Each four-part volume contains 24 plant portraits reproduced from watercolour originals by leading international botanical artists. Detailed but accessible articles combine horticultural and botanical information, history, conservation and economic uses of the plants described.

Published for the Royal Botanic Gardens, Kew by Wiley-Blackwell Publishing.
See the Wiley-Blackwell Subscription Information page for rates (for both print and online).

Changing the name

Adrian Hardy Haworth (1768-1833), who originally described the plant, was a keen amateur entomologist and botanist who was particularly interested in succulents and wrote Observations on the Genus Mesembryanthemum: In Two Parts, published in London, 1794.

Until 1926 Trichodiadema densum was known as Mesembryanthemum densum. The name Trichodiadema was applied by the German botanist Schwantes and describes the plant well, referring to the circlet of bristly hairs at the tip of each leaf (tricho meaning hair, and diadema, crown).

Uses

Trichodiadema densum is cultivated as an ornamental. In South Africa, the roots of Trichodiadema species are used for making a fermented honey beverage called iQhilika.

Cultivation

Propagation of Trichodiadema densum is by seeds or cuttings.

This species at Kew

Trichodiadema densum is growing in the Princess of Wales Conservatory, in the ’Living Stones’ collection in the dry climate section.

Alcohol-preserved specimens of Trichodiadema densum are held in Kew’s Herbarium, where they are available to researchers from around the world, by appointment. The details of one of these specimens can be seen on-line in the Herbarium Catalogue.


References and credits

Goldblatt, P. & Manning, J. (2000). Cape Plants. A Conspectus of the Cape Flora of South Africa. Strelitzia 9. National Botanical Institute, Cape Town/Missouri Botanical Garden, St Louis.

Radcliffe-Smith, A. (1998). Three-language List of Botanical Name Components. Royal Botanic Gardens, Kew.

Raimondo, D. et al. (2009). Red List of South African Plants 2009. Strelitzia 25. South African National Biodiversity Institute, Pretoria.

Sims, J. (1809). Mesembryanthemum densum. Curtis’s Botanical Magazine 30: t.1220.

Kew Science Editor: Martyn Rix
Kew contributors: Steve Davis (Sustainable Uses Group)
Copyediting: Malin Rivers

Although every effort has been taken to ensure that the information contained in these pages is reliable and complete, notes on hazards, edibility and suchlike included here are recorded information and do not constitute recommendations. No responsibility will be taken for readers’ own actions. Full website terms and conditions.




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