Habit of spiny emex

Young plant


Flower buds

Flowers are not very noticeable.

Spiny fruits

Stem and seedling

Scientific Name

Emex australis

Common Names

spiny emex, three cornered jack, double gee, cat's head




South Africa

Distinguishing characteristics

An annual herb spreading from a dense rosette with a thick taproot. This herb spreads horizontally with the ends growing upward.

Leaves dull green, pear shaped, tip broadly rounded, base as-if-cut-off to heart shaped, margins with finely shallow rounded teeth.

Flowers are not very noticeable and have no stalk. They are in auxillary clusters, that is, forming where the leaf meets the stem. 

Fruits (burrs) are in clusters with 3 hardened spines, are triangular in cross section with the angles somewhat rounded and are brown in colour.


Other plants easily confused with this plant

E. spinosa, less widespread in nature, has burrs half the size with spines half as long as those of E. australis.

Sources & References

"Weeds - an illustrated botanical guide to weeds of Australia" by B. A. Auld and R. W. Medd.

"Flora of New South Wales" editor Gwen J. Harden, Royal Botanic Gardens Sydney.

Royal Botanic Gardens & Domain Trust, Sydney Australia (1999 - 2005) 'PlantNET FloraOnline' http://plantnet.rbgsyd.nsw.gov.au/


Prepared by Justin KY Chu, July 2005

Checked by Dr Peter Michael, July 2005