Seed Morphology and Anatomy in Salvadoraceae (Brassicales) : Systematic and Evolutionary Implications

Abstract

To understand the evolution of seed character in Brassicales, we investigated the mature seed morphology and anatomy of four species in all three, poorly understood genera of Salvadoraceae (Azima, Dobera, and Salvadora). The seeds of Salvadoraceae are straight (i.e., not reniform), exarillate, and exalbuminous with a straight embryo. The seed coat is composed of only a testa and lacks a tegmen (including an exotegmen). The thick, multiplicative (except in A. sarmentosa) testa has no vascular bundles. The combination of seed and seed coat characteristics supports Salvadoraceae as distinct from the other Brassicales. Evolutionary trends in seed and seed coat (integumentary) characters in Brassicales, particularly the relationships of Salvadoraceae with Bataceae and Koeberliniaceae, are briefly discussed.