Petrophile is a genus of around 40 species, all occurring only in Australia. They are found in the southern half of the continent in temperate regions. Most are small to medium sized shrubs having flower clusters arranged in elongated or globular heads. The fruits are also elongated or globular in shape and the appearance of the fruits gives rise to the common name of “conebushes” or “coneflowers”. The genus is closely related to Isopogon.
Petrophile biloba is a small shrub up to about 2 metres high. The leaves are about 15-18 mm long and divided into flattened segments. The small flowers are pink in colour and occur in small clusters from the leaf axils. Flowering occurs in spring. The fruit is an small, oval shaped cone containing numerous seeds protected by woody bracts. The fruits remain on the plant for an indefinite period and only release the seeds after a fire or the death of the plant.
Petrophiles are not often cultivated but P.biloba would be a spectacular addition to a native garden. Although a western species, it is more reliable in humid east coast gardens than many other species from the west. However, that is not to say that it is an easy plant to maintain in those areas but it has been grown to flowering stage. It performs best in areas with dry summers and well drained soils. A sunny position will produce the best flowering but some shade is tolerated. It will withstand light to moderate frosts.
Propagation from seed is relatively easy and no pretreatment is necessary. Cuttings on firm, current season’s growth are also successful but may be slow to strike.
Photo: Margaret Pieroni