We analyzed DNA sequences of the plastid gene matK to infer phylogenetic relationships among angiosperms. Our sample includes seven monocot families (Anthericaceae, Asparagaceae, Convallariaceae, Joinvilleaceae, Poaceae, Restionaceae, and Trilliaceae) and 19 dicot families (Amborellaceae, Anthospermataceae, Brassicaceae, Calycanthaceae, Ericaceae, Fabaceae, Hamamelidaceae, Hernandiaceae, Illiciaceae, Lauraceae, Loganiaceae, Magnoliaceae, Monimiaceae, Nymphaeaceae, Paeoniaceae, Rosaceae, Rubiaceae, Saxifragaceae, and Scrophulariaceae). The tree is rooted with three families of conifers (Pinaceae, Cupressaceae, and Taxaceae) plus Gnetum (Gnetaceae). Including all species (Amborella and Illicium are missing the 5' one-third of the gene), the angiosperms are strongly supported as monophyletic. The base is a polytomy of six lineages: Amborella, Illicium, monocots, Nymphaeales, magnoliids, and tricolpates. Magnoliaceae are sister to all other members of the Magnoliid complex sampled. Saxifragales species form a clade with the rosids that is sister to the asterid clade. When Amborella and Illicium are excluded from the analysis, a single most parsimonious tree is recovered with a CI of 0.47 and an RI of 0.70 excluding uninformative characters. This tree shows Nymphaeales (bootstrap of 100%) as sister to the other angiosperms; the latter are divided into two large clades with the magnoliids (99%) sister to the tricolpates (97%). Additionally, the Nymphaeales are supported by a 12-bp insertion, the monocots by a different 12-bp insertion, and the tricolpates by a 9-bp deletion.

Key words: angiosperms, cladistics, evolution, matK, phylogeny