An erect, sparsely-foliaged shrub to 2.5 m high.
It is found mostly on the central coast of NSW, extending into the south coast and central tablelands; as far north as the upper Blue Mountains (north of Katoomba) and as far south as towards Nelligen and Marulan.
It is typically found in dry sclerophyll forest and wet and dry heath on sandy / sandstone-based soils.
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 20 cm long overall by about 5 cm wide, deeply divided with secondary divisions, with the undivided stalk shorter than the divided part; segments are terete; dark green to mid green in colour.
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 yellow or cream, to 10 mm long, hairless. Forming ovoid clusters to 40 mm long on comparatively longer stalks to 30 mm long.
The fruit is technically a nut (which differs to a lot of other genera). 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. Each nut is about 4 mm long and is hairy. The fruits remain on the plant for an extended time, and only release the seeds after a fire or the death of the plant.
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.
This species requires a sandy, 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 is advised after flowering.
Do not apply strong fertilisers that are high in phosphorus.
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.
This species is known to hybridise with Petrophile pulchella
This petrophile can be distinguished from the related P. pulchella which has flowers heads that are sessile or on peduncles up to 10 mm long.
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. This species can be seen in vast quantities in sandstone areas 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
pedunculata – Latin – referring to peduncle – the inflorescence stalk of this species is much longer than that seen in other species.
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 pedunculata profile page https://en.wikipedia.org/wiki/Petrophile_pedunculata
Plants of South Eastern NSW – Lucidcentral/Online identification app – Petrophile pedunculata profile page https://apps.lucidcentral.org/plants_se_nsw/text/entities/petrophile_pedunculata.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.