The coastal habitats of this long-lived perennial herb are grassy cliffs, sand dunes and shingle. Inland, it grows on limestone rock outcrops and cliff ledges. S. nutans is mainly a plant of shallow, drought-prone, calcareous soils on chalk and limestone, but it also occurs on acidic soil overlying shingle. It has occurred as a casual at ports and on railway banks. Reproduction is usually by seed, but can be vegetative by procumbent stems rooting at the nodes. Lowland.
A perennial herb of shallow, well-drained, light calcareous soils. As a native plant, it is confined to Breckland grass-heaths and roadsides, where open, disturbed ground provides sites for seedlings. Mature plants can survive for a while in denser swards, but are eventually excluded. It occurs elsewhere as a casual. Lowland.
This ascendant, bushy annual regenerates freely from seed and occurs as a casual or naturalised garden escape on rubbish tips and waste ground. Lowland.
An erect to ascendant perennial with a slightly woody base, found naturalised on a bank by Lochan na Lairige below Ben Lawers (Mid Perth). Upland.
A perennial herb occurring on rocky sea-cliffs from the lowest zone of vascular plants to cliff-top grassland, on seaside walls, shingle banks and on drift-lines. It can tolerate high levels of nutrient enrichment, and can be abundant on cliff-tops adjoining sea-bird colonies. It also occurs rarely on upland lake shores, streamsides, river shingle, cliffs and in gullies. Artificial habitats include metalliferous mine spoil, disused railway lines, ballast and tips. 0-775 m (Fairfield, Westmorland), and to 970 m in the Scottish Highlands.
S. vulgaris is a perennial herb found in a wide range of soils in open and grassy habitats, including cultivated and abandoned arable fields, rough pasture, roadside verges, quarries, gravel-pits, railway banks, walls and waste places. It is able to tolerate partial shade and may grow in open woodland and on hedge banks. 0-360 m (Shap Summit, Westmorland).