In Cycas whorls of scales alternate with large pinnate leaves.
There are con siderable irregularities, how ever, in this respect, and the number of leaves in different whorls is not always uniform, as may be seen in Lysimachia
The female flower is a small bud-like cone situated at the apex of a small branch, and consists of two or three whorls of two or three scales.
Of these whorls the two internal, forming the sporophylls, constitute the essential organs of reproduction; the two outer whorls are the protective coverings or floral envelopes.
In this way are formed the familiar feathery colonies of Plumularia, in which the pinnules are all in one plane, while in the allied Antennularia the pinnules are arranged in whorls round the main biserial stem.