Adenium swazicum
Family: Apocynaceae
Common Names: summer-flowering impala lily
Synonyms: Adenium obesum ssp. swazicum
Geographic Origin: Adenium swazicum is native to the open, dry woodlands and grasslands within Swaziland, southern Mozambique, and South Africa.
Description: A. swazicum is a dwarf, tree-like succulent that reaches a maximum of 2.5 feet in height. The trunk is thick and enlarged, with mature plants possessing massive roots, while younger plants demonstrate a visible caudex. A. swazicum can be differentiated from other Adenium species by the weaker greenish-gray stems and branches, and smaller overall form. The deciduous leaves are long, narrow, and glossy-green, usually lighter in color than other Adenium plants.
During the summer, both leaves and flowers will be present, appearing in apical clusters and terminal inflorescences, respectively. The pink to purple flowers are showy and uniformly colored, although they occasionally possess darker throats. Brown, pod-like fruits will follow in twin pairs, and seeds will be attached to a dirty white tuft of hair.
Interesting Features:
  • The genus Adenium is considered by some botanists to only include a single variable species – Adenium obesum – and therefore many use A. obesum ssp. swazicum as the scientific name.
  • Due to habitat destruction from sugar-cane plantations, and harvesting for medicinal or horticultural purposes, the summer flowering impala lily is listed as Critically Endangered on the Red List of South African Plants.
  •  Uses: Horticulturists harvest the entire plant for use in cultivation, while traditional healers use the tubers for medicinal purposes.
    • Toxic sap is produced from the trunk, and has been used to poison arrows, kill parasites, and treat heart failure or skin disease when diluted.

Cultivation and Care:
     - Watering: Low
  • Water sparsely during spring, summer, and fall, only irrigating when soil has become completely dry.
  • Do not provide any moisture during the cold season to avoid killing the plant, as Adenium species require a dry overwintering period.
     - Soil Type: Will not grow in heavy or water-logged soil – provide rich, organic peat or bark-based succulent or cactus soil supplemented with 50% perlite or sand.
     - Lighting: Adenium swazicum tolerates full sun to partial shade, but will have decreased growth and will not flower under low light conditions.
  • In addition to light, warmth should also be provided for optimum growth.
     - Propagation: The summer flowering impala lily can be propagated through grafting, cutting, or through seed.
  • Although the species easily reproduces through seed within its natural habitat, cuttings or grafting are the preferred methods in cultivation, as the species has very slow growth.
     - Cold tolerance: 30-50°F, USDA hardiness zones 10a to 11b
     - Special Accommodations: Although A. swazicum tolerates temperatures down to 30°F for short periods, it should be taken indoors below 50°F. Leaf drop and yellowing may occur under cold conditions, and the plant will die if exposed to any moisture.
  • At the same time, a low dose of liquid fertilizer should be provided each week during the growing season.
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​Sources:
  1. University of Florida
  2. South African National Biodiversity institute
  3. World of Succulents
  4. Cactus Art Nursery
  5. Succulents Network
  6. The Cactus King
  7. Research Gate