The other major group of gymnosperms apart from the conifers, consisting of long-lived flowerless plants with palm-like or fern-like, leathery fronds springing from a short trunk or caudex. Male (pollen) and female (seed) cones are borne on separate plants and may be quite large. Cycads are an ancient group, most abundant in the ‘age of dinosaurs’ (Jurassic and Cretaceous) just before the flowering plants began to diversify. Less than 200 species survive today, confined to warmer regions of the world. Examples are Cycas, Encephalartos, Zamia.
A variety of plants, in cluding Cycas revoluta and C. circinalis, from which cycasin has been isolated.