Synonymy

Armeria maritima-Aster tripolium provisional nodum Ivimey-Cook & Proctor 1966 p.p.; Crithmum maritimum rock-crevice community Proctor 1975; Crithmion communities Shimwell 1976 ms.

Constant species

Crithmum maritimum, Spergularia rupicola, Festuca rubra, Armeria maritima.

Rare species

Parapholis incurva, Limonium recurvum (and probably other apomicts of the L. binervosum group, e.g. L. paradoxum, L. transwallianum; see also Ingrouille 1981).

Physiognomy

The Crithmo-Spergularietum has a low-growing, very open cover of scattered vascular perennials rooted in rock crevices. The distribution of the plants and the overall appearance of the vegetation are strongly influenced by the nature of the substrate and, in general, none of the association constants can be said to be truly dominant, though all but Spergularia rupicola may be particularly abundant in individual stands. Plantago maritima is the most frequent associate throughout the association. Bryophytes are rarely conspicuous with only Schistidium maritimum and Tortella flavovirens recorded very occasionally. The only lichens are epilithic.

Sub-communities

Typical sub-community: Crithmo-Spergularietum rupicolae typicum Géhu 1964. The four association constants here account for the bulk of the vegetation cover and, of the associates, only Plantago maritima and P. coronopus attain a constancy above I.

Iula crithmoides sub-community: Crithmo-Spergularietum rupicolae plantaginetosum coronopi Géhu 1964 p.p. Spergularia rupicola is rather less frequent in this sub-community but Inula crithmoides and Plantago coronopus are both constant and the former may be abundant. Limonium binervosum (including its apomicts), Parapholis incurva and Desmazeria marina are all preferentially frequent.