North African Catchfly or Mountain Carnation (Silene pseudoatocion), an obscure member of the genus, originating in Spain and Algeria, which has been distributed around the world in modern speciality horticulture.
The species is poorly documented online, and it is unclear if it has ever been a routine nursery feature or was mainly introduced through networks of botanic gardens and private collectors. Even in Spain, the range of the plant appears to be limited, such that newly identified occurrences there merit journal reports.
In South Australia, the species has been recorded around Adelaide and from several more far-flung coastal and inland sites since 1970. Mountain Carnation has been collected twice in Victoria since 2000: from coastal dunes at Port Fairy and from a sandy roadside in the middle of the Mornington Peninsula.
A year ago I photographed plants of this species, spreading from a presumably intentional planting in a Northcote front yard into cracks in the adjacent paved drive. Now here it is represented by a handful of plants in naturalised conditions along a trail in Yarra Bend Park. Other than a poorly attested accession from the botanic gardens, this is apparently the first record for Melbourne, and has been dutifully added to iNaturalist.