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 plant is damp, sandy, gravelly places, bare spots on heathy places. The habit is erect, inversely pyramidal. The stem is repeatedly forked. The leaves are egg-shaped, entire, acute, 3-5-nerved, stalkless, rather succulent. The flowers are solitary, small, white, in the axils and terminal. The sepals are deeply acutely 3-cleft, united below, as long as the petals, which are oblong. The parts of the flower are in fours. The plant is 1-3 in. high, flowering in July and August, and is a herbaceous annual.
The habitat of this species is dry pastures, heaths, downs. The plant has the grass habit. The stems are square in section, one or more, much branched, slender, hairless, bluish-green. The leaves are opposite, linear to oblong, inversely egg-shaped, the upper alternate, lance-shaped. The flowers are white, small, in a forked panicle, spreading. The buds are drooping. The sepals are elliptic, acute, toothed, 1-nerved, long-pointed. The petals are distinct, acute, oblong, blunt. The plant is 2-10 in. high, flowering between June and August, and is a herbaceous annual.