This cushion- or mat-forming perennial herb is confined to base-rich substrates. It is characteristic of a species-rich dwarf-herb ledge community on Scottish mountains. However, it also grows in sparse vegetation on exposed mountain plateaux, serpentine fell-fields, cliff-slopes and stabilised sand dunes. From sea level in W. and N. Scotland to 1305 m on Ben Macdui (S. Aberdeen).
An annual occurring as a garden escape or throw-out on rubbish tips and waste places. It is usually casual, but may persist for a few years in disturbed, open sites, reproducing by seed. Lowland.
This erect, slender annual occurs as a casual garden escape on rubbish tips and in waste places. Lowland.
An annual of open habitats on free-draining sandy soils. In coastal regions, it is found on stabilised dunes and sandy shingle, in open pastures and on waste ground; inland it also occurs at the edges of tracks across heathland, in abandoned arable fields and on commons. It flowers freely, but good seed production occurs only in hot summers. Lowland.
A short-lived perennial herb that is most prominent in lightly shaded habitats such as hedgerows, coppices, and woodland clearings and rides. It can, however, survive in deep shade in a non-flowering form. It also occurs in coastal habitats, including sheltered cliff-top grassland and scrub, rock crevices, sea-bird rocks and stabilised shingle, and is also found on montane screes and cliffs. 0 - 1065 m (Lochnagar, S. Aberdeen).
The perennial S. x hampeana is found predominantly on woodland margins and rides, on scrubby banks and in hedgerows. It shows quite high levels of fertility, and back-crossing to the parents may give rise to hybrid swarms. Lowland.
A winter-annual of cultivated and disturbed ground, mainly in arable fields on (often acidic) sandy or gravelly soils, and on old walls and waste ground. It also occurs in open, drought-prone coastal grassland on banks and cliffs, and on sand dunes in the Channel Islands. It is sensitive to low winter temperatures. Lowland.
A mostly erect perennial, similar to S. nutans, which is naturalised on chalky roadside banks and chalk quarries between Dartford and Greenhithe (W. Kent). It is found as a casual garden escape elsewhere. Lowland.
S. latifolia is usually a short-lived perennial, but it may occasionally be annual or biennial. It occurs on arable land, in hedge banks and waste places, being most abundant on deep, well-drained soils. Mainly lowland, but reaching 425 m in Atholl (E. Perth).
This spring-germinating annual occurs mainly on cultivated land, but sometimes also on open waste ground. It is mostly found on dry, sandy and calcareous substrates, but also on heavier soils over oolitic limestone. Lowland.