Cape spinach

Emex australis
Herb
Basal
Simple
Inconspicuous
Green

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.

Common names 
Also known as: bull head, cat's head, devil's face, devil's thorn, double gee, giant bull head, goathead, goat's head burr, southern three-corner jack, spiny emex,
Family 
Polygonaceae
Deciduous 
No
Flowering time 
Winter
Native/Exotic 
Exotic
Origin 
Native to southern Africa
Notifiable 
No
State declaration 
Nil
Council declaration 
Class R – Reduce populations
Known distribution 

A very widely naturalised species that is particularly common in the sub-coastal districts of temperate Australia. It is most abundant in the western and southern parts of Western Australia and is also common in parts of New South Wales, Victoria, South Australia and south-eastern Queensland. Also present in other parts of Queensland, in the southern parts of the Northern Territory and in Tasmania (i.e. on Flinders Island).

It is also regarded as a weed in the USA, Taiwan and New Zealand.

Habitat 

E. australis is adapted to grow on a wide range of soil types from loamy sands to clay loams, usually neutral to slightly alkaline and it can tolerate temperate to subtropical climates. It thrives in open, disturbed and nutrient-enriched environmentsso it is predominantly a weed of agriculture. It is a relatively weak competitor, being out-competed by grasses and legumes, but it can dominate in habitats where environmental conditions such as drought or unseasonal rains can modify pasture composition. In natural ecosystems it is typically restricted to areas disturbed by wind or water such as water holes, granite rocks, edges of creeks and alluvial flats or areas disturbed by the native fauna, for example by sea birds on the Abrolhos Islands of Western Australia or by Cape dune mole rats in Western Cape Province, South Africa.

Impact and control methods 

Doublegee can infest crops and pastures. Its woody fruits can damage the feet of livestock, particularly lambs, and dogs. Doublegee plants can be toxic to livestock.

Stem and leaves 

Stems: mostly prostrate, to 50 centimetres long, several arising from the crown, hairless, ribbed, fleshy and purple at the base and nodes.

Leaves: triangular to oval, hairless, each leaf stalk surrounded by membranous sheath at the base.

Flowers and fruits 

Flowers: male and female flowers are separate and inconspicuous. The male flowers are in clusters on small stalks, while the female flowers are almost without a stalk and form in the leaf axils.

Fruit: woody and hard, 7 to 11 millimetres long and triangular in longitudinal cross section, each angle extending to rigid sharp spine. There are four pits on each face. Changes from green to brown when mature.

Seed: triangular and one per fruit.

Reproduction and dispersal 

E. australis only reproduces by seed, which can be carrid by livestock or may penetrate and be carried by vehicle tyres.

Similar species 

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