This site and its content are under development.

Sedum forsterianum Sm., Rock Stonecrop

Account Summary

Introduced, neophyte, a very rare garden escape, perhaps only casual.

1949; MCM & D; on bridge over Woodford River, at Aghalane.

Growth form and British and Irish status

This succulent, grey-leaved, mat-forming stonecrop is regarded as native in parts of Wales and SW England. Elsewhere in B & I, it is cultivated and is widespread at least in lowland Britain as a naturalised, sometimes persistent, garden escape. It is recorded much more rarely in Ireland, however, and although sometimes plants here survive beyond garden confines for up to five years, they probably fail to reproduce, and thus are only casual (New Atlas).

There has been and remains considerable confusion between this species and the very similar introduced, cultivated and escaped S. rupestre L. (= S. reflexum L.) (Reflexed Stonecrop), to the extent that, in FNEI 3, Hackney issued a caution with regard to the reliability of older records in the three VCs of NE Ireland (H38-H40). Following this, Reynolds (Cat Alien Pl Ir) re-examined Irish herbarium material and discovered that most 19th and 20th century records of S. rupestre are not the Linnaean species, but really refer to S. forsterianum.

Fermanagh occurrence

In almost all other Irish VCs where records of S. forsterianum have been published, details of only one or two stations are reported (eg FNEI 3; Cat Alien Pl Ir). In Fermanagh, we are above the Irish VC average in having a total of four records. The details of the other three records are: road between Tempo and Brougher Mountain, 1953, MCM & D; by main Enniskillen road, near Coollane, July 1988, RHN; and Lisbellaw Old Quarry, 3 July 1994, RHN.

Locally, Rorbert Northridge and the current author (RSF) regard S. forsterianum as a very rare and only casual garden escape, typically occupying dry and droughted, rocky or stony habitats. It is reputed to be most typically associated with dolerite and other basic igneous rocks producing thin, dry and moderately acid to neutral soils of low nutrient status. In common with other small Sedum species, it is a poor competitor with tall grasses and herbs, but is very tolerant of drought and disturbance (Sinker et al. 1985).

As the English common name suggests, Rock Stonecrop is quite commonly grown in old-fashioned rock or alpine gardens. In the current author's experience of this, it sometimes remains stubbornly vegetative, completely failing to produce any of its yellow, star-like flowers. In churchyards and cemeteries, S. forsterianum is also quite frequently planted on gravel-covered graves, probably on account of its low carpet-forming, grey foliage, its drought resistance, and consequent ability to survive considerable periods of neglect growing on undisturbed stony surfaces with very little soil.