An erect shrub that grows to a height of 2 metres (often seen smaller).
It has a large geographic range in NSW with a patchy distribution on most of the coast and tablelands areas, as well as, the north-western slopes. Patches occur to the east of Queanbeyan in the south; in the Blue Mountains and north of Lithgow, as well as the Southern Highlands near Hill Top; with scattered records in the Central Coast and Hunter Valley; then with a disjunction to north of Taree where it grows from the coast to the northern tablelands, up to the border, as far west as Warialda. It extends into Queensland, in a patchy distribution, to the Blackdown Tableland (west of Rockhampton).
It grows in heathland and dry sclerophyll woodland and forest, usually on deep sandy soils.
Has branchlets and leaves that have silky grey hairs when young.
Petrophile spp. have a somewhat complicated leaf structure. Leaves are simple but are strongly divided into segments, usually in the upper half of the leaves with the lower half acting as a linear petiole or stalk. This can be referred to as strongly pinnatisect. Sometimes, leaf segments are ternately-divided (into groups of 3). The leaf segments are also terete (tubular). They are arranged alternately. In this species, leaves are to 11 cm long overall and about 4 cm wide, deeply divided several times, with the undivided part (stalk) longer than the divided part and with segments terete, blue-green / grey-ish to green in colour and not overly prickly.
Petrophile spp. have many small flowers arranged in a compressed spike or ‘head’, formed in the leaf axils and terminals, with all flowers surrounded by bracts which become more woody as the inflorescence begins to fruit. Flowers have 4 tepals in the perianth, a typical Proteaceae feature, but flowers are more symmetrical in this genus. In this species, flowers are white to yellow, to 14 mm long, with appressed silky hairs, in dense, more or less ovoid clusters to 40 mm long; mainly appearing in September to January. The stalk of the inflorescence is about 10 mm long.
The fruit is technically a nut (which differs to a lot of other genera in the family). The nuts are formed within the resulting fruiting cluster of the inflorescence which has an elongated cone-shape and holds the nuts in the woody bracts. The fruit in this species is nut about 5 mm long, fused with others and inside the bracts, in the cone-shaped cluster. The nuts have longer hairs than other species.
Petrophile species were first introduced to cultivation in the 18th century, but these days are rarely seen outside specialist botanical and enthusiast’s gardens.
They are known to be cultivated and can do well in the right conditions.
Not much is known about the cultivation of this species but can likely be cultivated.
Likely best on a free-draining soil in full sun.
They may die quickly due to strong wind or poor drainage due to heavy rain. But well worth growing.
Pruning after flowering is recommended.
They can be grown from seed which germinates well if fresh, although germination times may be variable from the same batch and so seed trays should be kept for some time before being discarded. Germination in some species is improved by smoke treatment, but experimental work is lacking in many taxa. Another thought for improving germination may be to remove the hairs on the nuts that seems to repel water, or nick the nuts to allow water to get to the seed embryo.
Propagation can be carried out from cuttings taken from semi-firm new growth, and treated in the regular way with the warning that the hairy leaved species should not be misted too much for fear of fungal disease.
Seeds are available commercially.
This petrophile can be distinguished from the related Petrophile pulchella by its finely hairy new growth
Petrophile is a genus of approximately 63 species with the greatest diversity being in the south of Western Australia. They also occur in Queensland, NSW and South Australia. NSW currently recognises 4 species.
Petrophile spp. will generally generate from seed after fire.
Petrophile – from the Greek words petra (πέτρα) = “stone” or “rock” and philia (ϕιλία) meaning “loving” or “preferring” – referring to many species that live on rocky-habitats
canescens – Latin meaning “grey-ish” – referring to the hue on the leaves due to the hairs.
This species is not considered to be at risk of extinction in the wild.
The Australian Native Plants Society (Australia) fact sheet for Isopogon and Petrophile: https://anpsa.org.au/APOL29/mar03-3.html
Wikipedia – Petrophile canescens profile page https://en.wikipedia.org/wiki/Petrophile_canescens
Plants of South Eastern New South Wales – Lucidcentral/Online Identification app – Petrophile canescens profile page https://apps.lucidcentral.org/plants_se_nsw/text/entities/petrophile_canescens.htm
Wrigley, J.W. & Fagg, M.I. (2001). Australian Native Plants – Propagation, cultivation and use in landscaping. 4th edition. New Holland Publishers, Pty. Ltd. Australia.