Description: The Sphenopsida are terrestrial, vascular plants which lack flowers and reproduce sexually by spores. The herbaceous sporophyte consists of true roots, an underground rhizome and aerial jointed stems which bear leaves.
The leaves are scale-like and arranged in whorls at nodes with their lower parts fused together to form cylindrical sheaths.
Sporangia are borne on peltate sporophylls which are arranged in terminal cones or strobili. Spores are of one kind and elaters assist in the dispersal of the mature spores from the sporangia. The spores develop into one or two kinds of prothalli. After fusion of the gametes produced by the sex organs on the prothalli, the independent sporophytes develop.
Distribution and occurrence: World: 1 family, 1 genus, c. 30 species, cosmopolitan except for Aust and New Zealand. Australia: 1 species (naturalized).
Plants of this class were widely distributed during the Carboniferous and Devonian eras with only one genus surviving today.
Sometimes ranked as a Division, Equisetophyta.
Text by G.J. Harden
|One family in NSW: EQUISETACEAE|