Multigene analyses identify the three earliest lineages of extant flowering plants

Flowering plants (angiosperms) are by far the largest, most diverse, and mo st important group of land plants, with over 250,000 species and a dominati ng presence in most terrestrial ecosystems, Understanding the origin and ea rly diversification of angiosperms has posed a long standing botanical chal lenge [1], Numerous morphological and molecular systematic studies have att empted to reconstruct the early history of this group, including identifyin g the root of the angiosperm tree. There is considerable disagreement among these studies, with various groups of putatively basal angiosperms from th e subclass Magnoliidae having been placed at the root of the angiosperm tre e (reviewed in [2-4]). We investigated the early evolution of angiosperms b y conducting combined phylogenetic analyses of five genes that represent al l three plant genomes from a broad sampling of angiosperms, Amborella, a mo notypic, vesselless dioecious shrub from New Caledonia, was clearly identif ied as the first branch of angiosperm evolution, followed by the Nymphaeale s (water lilies), and then a clade of woody vines comprising Schisandraceae and Austrobaileyaceae. These findings are remarkably congruent with those from several concurrent molecular studies [5-7] and have important implicat ions for whether or not the first angiosperms were woody and contained vess els, for interpreting the evolution of other key characteristics of basal a ngiosperms, and for understanding the timing and pattern of angiosperm orig in and diversification. (C) 1999 Elsevier Science Ltd. All rights reserved.