Tribulus platypterus, the cork hopbush, is a species of flowering plant in the family Zygophyllaceae, which is endemic to the northwest of Western Australia. It is closely related to Tribulus suberosus.

It was first described by George Bentham in 1863 from a specimen collected by Francis Thomas Gregory in the Hammersley Ranges. An isosyntype (MEL 79454) collected by Gregory (east of the Hammersley Ranges) is held in the National Herbarium of Victoria. The specific epithet, platypterus, is derived from two Greek roots/words, platy- ("broad") and -pterus, ("winged"), and describes the plant as having "broad-winged" fruit.

Description

Tribulus platypterus is a spreading upright shrub which grows to a heights from 40 to 100cm high and spreading from 50 to 200cm. The stems usually lack corky bark except at the plant base. The leaves occur in unequal pairs, and have from 4–7 pairs of leaflets on a stalk which is 3–13mm long. Within each compound leaf the leaflets have short stalks and vary 4–23mm long by 2.2–8.3mm wide. The flower stalk is upright and 3.5–6.5mm long. The sepals are 6–8.5mm long, and have no covering or have sparse silky hairs on the upper surface, and densely hairy on the lower surface. The petals are elliptic, 10–11mm long, and not hairy. There are 10 stamens, which may all be fertile or some or all them may be shorter and staminodal. The longer filaments are 5.5–6mm long; and the shorter filaments are about 3mm long. The ovary is moderately to densely covered with white silky hairs, and has one ovule per cell. Both the style and stigma are 4.5–6mm long. The fruit is a ball-shaped 5-winged schizocarp (a fruit which splits into individual carpels), the wings of which give rise to the specific epithet of "broad winged", and is 12–18mm long by 15–21mm wide.

It mostly flowers from August to October.

Distribution & habitat

It is found in the IBRA Regions of the Central Kimberley, the Gascoyne, the Little Sandy Desert, the Murchison, and the Pilbara, in rocky areas, including creek banks and beds, and often in sand.

Conservation status

Under West Australian conservation laws it is deemed to be "not threatened".

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