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 Download authors' original
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