The plant division Gnetophyta or gnetophytes comprise three related families of woody plants grouped in the gymnosperms, a paraphyletic group of seed plant divisions. The gnetophytes differ from other gymnosperms in having wood vessels as in the flowering plants (Angiosperms or Magnoliophytes), and it is thought that Gnetophytes may be the group of spermatophytes most closely related to the flowering plants.
The Gnetophytes are divided into three orders, each containing a single family and genus:
The Gnetales consist of a single genus, Gnetum, which are mostly woody climbers in tropical forests. However, the most well-known member of this group, Gnetum gnemon, is a tree. The seeds produced are used to produce a crispy snack known as 'Keropok Belinjau' in Malaysia and Indonesia. The Malay name for this plant is 'belinjau'.
The Welwitschiales comprise only one species, Welwitschia mirabilis. It grows only in the deserts of Namibia. The plant is strange in having only two large strap-like leaves for all its life. These grow continuously from the base, and are usually tattered at the ends by flapping in the winds.
The Ephedrales consist of a single genus Ephedra, and are known as the jointfirs because they have long slender branches which bear tiny scale-like leaves at their nodes. Ephedra is reputed to have medicinal properties, but has recently been banned by the FDA due to harmful and potentially deadly side effects.
This was based upon the presence of vessels in some gnetophytes (all other gymnosperms have only tracheids, angiosperms have both tracheids and vessels) and a type of double fertilization seen in Ephedra.
The plants are dioecious, the pollen and ovules borne on stalked cones.
As stated in your book, the gnetophytes, together with the angiosperms, have been called anthophytes because of the presence of flowers or flower-like structures.
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