Bolax is a small genus of cushion-forming flowering plants in the carrot family, Apiaceae (order Apiales). It is endemic to the cool, windswept subantarctic regions of temperate South America, occurring naturally in Tierra del Fuego and on the Falkland Islands.
The genus is notable for its distinctive growth form: plants build dense, firm, prickly mounds that superficially resemble moss cushions but are considerably tougher and more rigid. The sole widely cultivated species, Bolax gummifera (Lam.) Spreng., forms cushion mounds up to 1.2 metres in diameter. It is evergreen and perennial, growing very slowly. Flowers appear in June and July and are pollinated by insects. The species is dioecious — flowers are either male or female and borne on separate plants — so both sexes are required for seed production; plants rarely flower at all in garden conditions.
Bolax has historically been treated by some authors as part of the related genus Azorella, and the two genera share similar cushion-forming habits and Andean–subantarctic distributions. Plants of the World Online currently accepts two species in Bolax. The genus yields an oleo-resin from incisions at the base of the main stem, which has traditional medicinal use as an antispasmodic and deobstruent.
Distribution
Bolax is endemic to temperate South America. Its range centres on Tierra del Fuego and the Falkland Islands, where it grows in exposed, windswept habitats typical of the Magellanic subantarctic zone.
Ecology
Bolax gummifera grows best in full sun on light, well-drained, gritty or sandy soils with a mildly acid to mildly alkaline pH. It tolerates dry or moist conditions and withstands strong winds, but does not perform well under maritime salt exposure. Its cushion-forming habit is an adaptation to harsh, open, cold environments. It is not shade-tolerant.
Taxonomy Notes
Bolax is placed in the family Apiaceae, order Apiales. The genus has historically been subsumed into Azorella by some authors; Plants of the World Online and GBIF currently treat it as a distinct accepted genus with two species. The best-known species, Bolax gummifera, was described by Lamarck and combined by Sprengel (authorship: (Lam.) Spreng., published 1818).
