Figure 1.

Conflicting Phylogenetic Hypotheses involving the seed plants. Morphological evidence (synapomophic characterstics shared between angiosperms and Gnetales) have shaped the anthophyte theory, where these two taxa form sister groups (Panel A; [1, 2, 5]). In contrast, most molecular studies postulate gymnosperms as a monophyletic group sister to all angiosperms, and place the Gnetales as a sister group to the conifers (Panels B and D; [7–9, 15, 16]). Adding to the controversy, a recent study involving phytochrome genes ([13]; Panel D) has placed the Gnetales as basal gymnosperms, with Ginkgo and cycads as sister taxa branching after the Coniferales.

de la Torre et al. BMC Evolutionary Biology 2006 6:48   doi:10.1186/1471-2148-6-48
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