CLADISTICS OF THE SPERMATOPHYTA

A cladistic interpretation of seed plant phylogeny is presented that supports the traditional morphological hypothesis: [Cycadales-(Ginkgoales-(Coniferales-(Gnetales-Angiosperms)))]. Gnetales and Angiosperms are supported as sister groups of the Anaspermae. A sister-group relationship between Coniferales and Ginkgoales represents a paraphyletic group, because Coniferales and Anaspermae share a common ancestry (Mesospermae). Ginkgoales and Mesospermae are sister groups of the Cladospermae. Cycadales are supported as the most archaic Spermatophyta. A posteriori consideration of fossil taxa supports the conclusion that data from the fossil record are useful for confirming plesiomorphies of extant taxa. Fossil taxa with apomorphic character states are discussed as biasing for superficial accelerated transformations, which are probably unacceptable from the standpoint of morphological homology. © 1990 the New York Botanical Garden.