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.
Centanrium (Erylhraea) capitatum, R. and B - - The habitat of this species is downs and the South coast of England. The plant is erect, with the rosette habit. The stem is short, simple. The stem-leaves are egg-shaped, spoon-shaped, blunt, 3-veined. The radical leaves form a rosette, 3-5 nerved, with 3 long and 2 short veins. The flowering tufts are stalkless, some long-stalked tufts overtopping the primary tuft from the outer bracts. The flowers are stalkless, in close, terminal tufts, rose-colour, the cylindrical corolla-tube longer than the calyx, the top not narrowed, nor lengthening, the lobes oblong, blunt. The stamens are inserted at the base of the tube above. The capsule half-projects. The plant is 2-4 in. high, flowering in July and August, and is a herbaceous annual.
Gentiana lingulata, C. A. Agardh, b. precox, Raf. = 67. campestris, L., b. obtusifolia, Williams. - This plant is an early vernal flowering state of G. campestris, according to Mr. F. N. Williams (Prodr., p. 235), and not of G. amarella, with all the leaves blunt, the calyx - lobes unequal, and with tetramerous flowers. It flowers in May and June.
This species is regarded by Mr. F. N". Williams (Prodr., p. 235) as synonymous with G. campestris. It is an annual form, with the lower leaves egg-shaped to lance-shaped, and smaller flowers.
Yellow Wort (Blackstonia (Chlora) perfoliata, Huds.). - The habitat of this species is clay or calcareous banks and pastures, damp chalky places. The plant has the rosette habit. The stem and leaves are bluish-green. The stems are simple, the leaves enveloping them at the base, so that creeping insects cannot climb up the stem, and are square or round, several. The radical leaves are inversely egg-shaped to spoon-shaped, blunt, narrowed below. The stem-leaves are smaller, broadly egg-shaped, acute, in distant pairs, clasping the stem. The flowers are numerous, yellow (hence chlora), in a forked panicle. The calyx is divided to the base into 8 slender, narrow, linear, awl-like segments. The corolla-lobes are oblong, blunt, the tube ruptured by the ripe capsule. The stigmas are yellow, divided into 2 nearly to the base. The plant is 4-18 in. high, flowering from June to September, and is a herbaceous annual.