Conifers can produce multiseriate rays if the rays contain resin canals, and
Gnetales are all characterized by multiseriate rays.
Pearson,
Gnetales, Cambridge University Press, London, UK, 1929.
Keywords: Chhidru Formation, Palynomorphs, Monocolpate, Sulcate, Gymnosperms, Peltasperms,
Gnetales, Medullosales and Ephedralels.
Xylem hydraulic and photosynthetic function of Gnetum (
Gnetales) species from Papua New Guinea.
Phylogenetic relationships in Ephedra (
Gnetales): evidence from nuclear and choloplast DNA sequence data.
Several previously mentioned studies have used various gymnosperm groups (particularly the
Gnetales) as outgroup.
Conifers and most members of the
Gnetales (i.e., Ephedra and Welwitschia) express both prefertilization and postfertilization provisioning of embryo-nourishing tissues of the female gametophyte (Martens 1971; Singh 1978; Haig and Westoby 1989).
Pollen chambers are known from the earliest fossils of
Gnetales (Rothwell & Stockey, 2013).
Structure and function of female and bisexual organ complexes in
Gnetales. The International Journal of Plant Sciences 157: S113-S125.
Orbicules are omnipresent in
Gnetales: Ephedra (El-Ghazaly & Rowley, 1997; Doores et al., 2007), Gnetum (Camiel, 1966), and Welwitschia (Zavada & Gabarayeva, 1991).
What Brown most importantly recognized, albeit in a somewhat circumlocutious way, was that in cycads, conifers and
Gnetales, among extant seed plants, the ovules receive pollen directly, whereas in flowering plants the ovule, being enclosed within a carpel, cannot receive pollen, that being the function of the stigma.
Rudall is doubtful that the monocot cambium is equivalent to secondary thickening meristematic activity in non-monocot angiosperms and
Gnetales, and indeed, it is not.