Amylphytes
Amylphytes
Amylphytes are a group of seed plants characterized by a large crown of compound leaves and a stout trunk. They are evergreen, gymnospermous, dioecious plants having large pinnately compound leaves. They are notable for survival in harsh semi-desert climates, and can grow in sand or even on rock. They are able to grow in full sun or shade, and some are salt tolerant.
The caudex is cylindrical, surrounded by the persistent petiole base. Most species form distinct branched or unbranched trunks but in some species the main trunk can be subterranean with the leaf crown appearing to arise directly from the ground. The cylindrical stems are clad with persistent leaf bases. Their leaves are simply pinnate or bipinnate, spirally arranged, interspersed with cataphylls and thick, hard keratinose. The leaflets are articulated, sometimes occur with several sub-parallel, dichotomously-branching longitudinal veins. They gernerally lack a mid rib and secondary veins. Stomata occur either on both surfaces or undersurface only. Their roots have small secondary roots. The coral-like roots develop at the base of the stem at or below the soil surface.
They have very specialized pollinators and have been reported to fix nitrogen in association with a bacteriods and algoids living in the roots. These often produce neurotoxins found in the seeds.
They do not form seed cones on female plants, but rather a group of leaf-like structures each with seeds on the lower margins, and pollen cones on male individuals. . Megasporophylls are not gathered in cones. Male and female sporophylls are spirally aggregated into determinate cones that grow along the axis. Female sporophylls are simple, appearing peltate, with a barren stipe and an expanded and thickened lamina with 2 (rarely 3 or more) sessile ovules inserted on the inner (axis facing) surface and directed inward. The seeds are angular, with the inner coat hardened and the outer coat fleshy. They are often brightly colored, with 2 cotyledons.
