and this in turn has been linked with changes in the distribution of parenchyma cells." Now that we know that
Gnetales are conifer derivatives (Bowe et al., 2000; Burleigh & Mathews, 2004), and that
Gnetales have attained, parallel to angiosperms, essentially all of the important anatomical features of angiosperm wood (Carlquist, 2012b), we have a source for demonstrating quite dramatically pathways of wood evolution in vessel-bearing angiosperms and their significance.
Ephedra (Ephedra intermedia) belongs to family Ephedraceae and is a genus of nonflowering plants, related to
Gnetales, very near relatives of angiosperms [3].
Careful comparison of these taxa with extinct and extant plant groups revealed the prevalence of following viz; Gymnosperm, Peltasperms,
Gnetales, Medullosales and Ephedralels.
The anatomical organization of leaves and woody tissues of Gnetum is very similar to those of dicotyledoneous plants (Fisher & Ewers, 1995) to the extent that
Gnetales is considered a phylogenetic link between Gymnosperms and Angiosperms (Shutov, Braun, Chesnokov, Horstmann, Kakhovskaya & Baumlein, 1998).
Otros trabajos que han aportado conocimiento sobre el grupo son el de Martens (1971) acerca de la anatomia, citologia y embriologia de las
Gnetales y el de Pant y Verma (1974), donde se hace un analisis de las caracteristicas de la epidermis y la cuticula en varias especies.
Motomura H, Noshiro S, Mikage M (2007) Variable wood formation and adaptation to the alpine environment of Ephedra pachyclada (
Gnetales:Ephedraceae) in the Mustang distict, western Nepal.
Following (Chase et al., 1993; Doyle et al., 1994; Soltis et al., 1997; Soltis et al., 2000; Zanis et al., 2003) a set of gymnosperms (specifically Gnetum and Ephedra (
Gnetales)) was designated as outgroup.
Extant seed plants comprise five clades [ILLUSTRATION FOR FIGURE 1 OMITTED]: cycads, Ginkgo, conifers, angiosperms, and
Gnetales (Ephedra, Welwitschia, Gnetum).
(2010) there is considerable diversity in male gametophytes amongst the four orders of gymnosperms (Cycadales, Ginkgoales, Coniferales and
Gnetales).