title: Chemosystematics of the gnetatae and the chemical evolution of seed plants1.
abstract: A survey of the secondary metabolites reported for EPHEDRA, WELWITSCHIA and GNETUM documents a far-reaching chemical similarity of these genera with the angiosperms. However, the different substitution patterns of the phenolics do not support a close phylogenetic link between the two groups. The most significant chemical difference between the Gnetatae and the angiosperms seems to be the widespread use of protective devices against oxidation such as O-methylation and formation of Schiff bases which are so frequent in angiosperms and nearly absent from the Gnetatae and other gymnosperms.
authors.affiliation: Instituto de Química, Universidade de São Paulo, 05508 São Paulo SP, Brazil.
authors.forename: O R
authors.initials: OR
authors.lastname: Gottlieb
authors.forename: K
authors.initials: K
authors.lastname: Kubitzki