Table of Contents
Gnetophyta: An Enigmatic Group of Seed Plants
A Class of Only Three Orders and as Many Genera
Ephedra
Gnetum
Welwitschia mirabilis
Peculiarities of Welwitschia
Characteristics of Gnetophytes
Ephedra Megagametophyte
Features Shared with Angiosperms
Megasporogenesis
Microsporogenesis
Sterile Ovules
Ephedra Male Strobilus
Double Fertilization in Gnetophytes
Fertilization in Ephedra
Fertilization in Gnetum
Prerequisites for Double Fertilization
Common Ancestry or ...
Convergence?
The Cladograms
Fossil Gnetophyte Record - Triassic/Jurassic
Fossil Gnetophyte Record - Cretaceous
Food for Thought
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