Electronic Flora of South Australia
Electronic Flora of South Australia
Census of SA Plants, Algae & Fungi
Identification tools

Electronic Flora of South Australia genus Fact Sheet


Synonymy: Not Applicable

Common name: Sheoaks.

Monoecious or dioecious shrubs or trees with slender wiry articulate branchlets; leaves reduced to small teeth in a whorl of 4-15 or more surrounding the summit of each article (joint) of the branchlet; branchlets with as many longitudinal ridges (phyllichnia) as there are teeth, the phyllichnia separated by grooves to which the stomates are confined.

Inflorescences consisting of alternating whorls of tooth-like bracts; within each bract 2 lateral scale-like bracteoles and a single unisexual flower; male inflorescences short to elongated catkin-like spikes; female inflorescences small globular or ovoid heads; male flowers consisting only of 1 or 2 hooded scale-like perianth-segments and one stamen; female flowers without a perianth, consisting of 2 fused carpels with 2 or rarely 4 ovules and with a reddish 2-branched style.

female inflorescence developing into a more or less woody cone with the 2 enlarged bracteoles of each flower forming 2 lateral valves, which open when the seed-like compressed winged nut (samara) is ripe; seed solitary, with 2 large cotyledons and a superior radicle, no endosperm, often with more than 1 embryo.

Distribution:  4 genera with 80 species from Australia to the islands of the Pacific and south-east Asia.

Biology: Dried specimens show some important differences from fresh material, notably in the cones and branchlets. The fruiting bracteoles of the cone are nearly always appressed to each other, enclosing the samara, when fresh; once the cone is removed from the plant, the bracteoles separate. The softer tissues of branchlets tend to contract when dried, so that features such as angularity or convexity of phyllichnia are emphasised in dried specimens. Anther colour is most obvious in fresh specimens.

Uses: A number of species are commonly planted as ornamentals and for firewood, especially overseas; the timber is now little used commercially. C. equisetifolia is used in stabilising coastal sands.

Taxonomic notes: The family is being revised by L. A. S. Johnson.

Key to Species:
1. Samaras dark-brown or blackish, shining; bracteoles of the fruiting cone thick and convex, often with a more or less separate angular or divided protuberance; teeth 4-many
1. Samaras grey or tawny, rather dull; bracteoles of the fruiting cone relatively thin and without any dorsal protuberances; teeth 5-many

Author: Prepared by L. A. S. Johnson and K. L. Wilson

Disclaimer Copyright Disclaimer Copyright Email Contact:
State Herbarium of South Australia
Government of South Australia Government of South Australia Government of South Australia Department for Environment and Water