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Extant Gymnosperm Phylogeny

Tuesday 2 November 2004, by Rebecca

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Molecular analysis have proved that Gnetales are not the Angiosperm sister-clade (Chaw et al., 2000). Angiosperms may have appeared during Jurassic from a group of fossil plants such as Bennetitales or Caytoniales.

Gymnosperms are plants with seeds ( Spermaphytes) but with a naked ovule: the ovule is not included in a carpel that is an apomorphic feature of Angiosperms. A leaf-life structure (homologous to a leaf), a scale or megasporophyll bears the ovule.

Gymnosperms are probably monophyletic and include:

- Cycadales (Cycas, Zamia) that are the more primitive Gymnosperms (Basal Gymnosperms),

- Ginkgoales, a sister-clade of the clade including Conifers and Gnetales,

- Gnetales (Ephedra, Gnetum, Welwitschia) are monophyletic and nested within Conifers,

- Gnetales are the sister-clade of Pinaceae.

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