This section is from the book "British Wild Flowers - In Their Natural Haunts Vol5-6", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
The habitat of this species is limestone and chalky soils, sandy shores. The habit is prostrate. The branches are wavy, the leaves linear, the inner sepals wedge-shaped below, shorter and narrower than the capsule. The flower-stalks are hairless, with smaller flowers, usually blue. The plant is 1-6 in. high, flowering from June to August, and is a herbaceous perennial.
The habitat of this species is chalk downs. It differs from P. amara, L., in the colour of the flowers, which are very small, dull-blue or bluish-white. The capsule is rounded below, narrowed to the base, and the leaves are less flesh)'. The plant is 1-3 in. high, flowering in June, July, and is a perennial.
The habitat of this species is dry soil and rocks, chalk hills. The habit is the rosette habit. The stem is weak, prostrate or ascending, nearly naked below, branched, the many branches rooting and proliferous, spreading in an umbel-like manner from the root. The radical leaves are in an irregular rosette, large, egg-shaped, blunt, those of flowering stems short, smaller, lance-shaped, elliptic. The stem-leaves are oblong. The flowers are blue. The calyx-wings are oblong or inversely egg-shaped, larger than the fruit, the veins branched, the lateral looping, with a branch above the middle of the central vein. The capsule is oblong, inversely heart-shaped. The lobes of the aril are unequal, the lateral half as long as the seed. The plant is 1-6 in. long, flowering from May to July, and is a herbaceous perennial.