Experimental Studies in Two Genera of Helenieae (Compositae): Blennosperma and Lasthenia

Abstract

The biosystematics of Blennosperma and Lasthenia (Compositae: Helenieae) are discussed. Blennosperma consists of B. nanum (Hook.) Blake, widespread and racially diverse in California; B. bakeri Heiser, a narrow California endemic; and B. chilense Less. of the central valley of Chile. Evidence presented suggests that B. chilense is an amphiploid species derived from ancestors similar to the modern California species. The line giving rise to B. chilense apparently developed during or after the Miocene, migrated to South America, and subsequently became extinct in North America. Lasthenia (sect. Lasthenia) consists of two closely related species: L. glaberrima DC. of Pacific North America and L. kunthii (Less.) Hook at. Arn. of Chile. On several grounds it appears that the Chilean species is a vicariad derived from populations established after long-distance dispersal from the northern hemisphere.