Dragon Trees and Mother-in-Law's Tongues

The dragon trees and mother-in-law’s tongues (Dracaena and Sansevieria) form a monophyletic group within Ruscaceae (Yamashita & Tamura 2000, Rudall et al. 2000, APG II 2003) of ca. 180 species found across the wet to dry forest spectrum in the Old World tropics as far East as New Guinea, with outliers in Hawaii, the Canary Islands and Madeira, the Caribbean and Central America (Govaerts 2007). The highest levels of species diversity occur in West/Central Africa (Dracaena) and Eastern/Southern Africa (Sansevieria), with a secondary centre of diversity in South (Sansevieria) and SE Asia (Dracaena). A number of species are important in both temperate and tropical horticulture; virtually very European garden centre, for example, stocks Dracaena and Sansevieria species among its houseplants. However, a number of authors over a considerable time period (e.g. Baker 1875, Brown 1914, Obermeyer et al. 1992) have postulated alternative classificatory approaches to two genera based largely on habit and degree of succulence. Bos (1998) reduced Sansevieria to synonymy with Dracaena in his treatment of Dracaenaceae, although he did not make the many new combinations required at specific level and thus uptake of the change has been limited.