Hairy Pink (Petrorhagia dubia) – Weeds of Melbourne

Hairy Pink (Petrorhagia dubia), one of a pair of Western Mediterranean species of the genus that were introduced to Victoria in contaminated seed. It can be differentiated from its compatriot, Childling Pink (P. nanteuilii), on the basis of having hairy mid-stem sections, while the gold standard for identification rests on differences in seed morphology that we won’t get into here.

Hairy Pink is widespread but easily overlooked across southern Australia. So diminutive is its form that one might also notice and wonder about one scattered pink flower, but forget to notice all the others. It has been spread throughout as a contaminant of harvested seed and hay, and now presumably as a hitchhiker on heavy machinery.

Digitised records suggest that the first Australian collection of Hairy Pink was made in Victoria near Mansfield in 1892; a collection the next year ‘near Port Phillip’ suggests that the plant was already inside the metropolitan as well. By 1909 it had been spread to various points across the middle of Victoria, and had showed up definitively within the Melbourne region at Williamstown. The species had also made it to NSW that year, and then appeared in WA by 1917.

Known in past times as ‘Wild Carnation’ and ‘Wild Pink’, the ‘carnation’ name meant that in the early 20th c. it was repeatedly confused by WA residents with the ‘Geraldton carnation weed’ (a Euphorbia covered on this channel earlier this spring). Hairy Pink is a plant with a minor but insidious presence, and it was associated with various animal poisonings of the sort that seemed to plague Australian farmers in the first century following the invasion. Forwarded to newspaper columnists for identification, the Pink was invariably dismissed as ‘a harmless, useless weed’, but one that should be prevented from spreading as ‘we have quite enough useless weeds already.’

The photographed plants infest the outer edges of a cut paddock, in transmission corridor parallel to the M80 Ring Road and on the adjacent sun-drenched slope of a revegetated creekline.