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 fields, banks, etc. The habit is erect, branched, with slender spreading stems. The flowers are small, pale-lilac, in crowded cymes. The fruit is softly downy or smooth, egg-shaped, and is crowned with the large, toothed, nearly regular, truncate, net-veined calyx. The empty cells are distant and slender, and the fertile cell is not corky. The plant is 6 in. to 1 ft. high, flowering in June and July, and is a herbaceous annual.
This species may be found as a weed in cornfields, on garden walls, where many similar weeds occur, and on hedgebanks. The plant is much-branched, and like the Common Lamb's Lettuce ( V. olitoria), except in the following respects. The radical leaves are spoon-shaped, those on the stem oblong. The flowers are pale-blue, in a dense cyme, forming a head. The bracts have a fringe of hairs. The fruit is flattened from front to back, boat-shaped, oblong, there being two large barren cells, and the fertile cell is not corky (as in V. olitoria), the cells being nearly equal. It is crowned with a nearly straight tooth. The barren and fertile cells are touching, with a deep furrow between. The plant is 2-8 in. in height. It flowers from April to June, and is a herbaceous annual.
The habitat of this species is cornfields and cultivated ground. The habit is as in the next, but it is more slender. The lower leaves are inversely egg-shaped, narrow below, the upper oblong. The bracts are fringed with hairs. The flowers are distant, in a loose cyme, repeatedly forking, pinkish-blue. The fruit is nearly round, swollen, with an erect, membranous, blunt tooth, the calyx forming a crown, the barren cells larger than the fertile, and swollen, with a narrow furrow in front, touching, the fertile cell not corky. The plant is 2-12 in. high. Flowers are to be found in July and August. The plant is herbaceous and annual.
This species is found in cornfields, cultivated ground, and on banks. The habit is similar to that of V. olitoria, branched, but slender. The flowers are flesh-coloured, borne in a loose, spreading cyme or corymb. The fruit is narrowly egg-shaped, flat, crowned with the small calyx, which is unequal, 4-toothed, and flat in front with a space, smooth, the fertile cells not corky, the empty cells smaller, and in a separate portion of the fruit wall produced at each end. The plant is from 2 in. to a foot high. It flowers in June and July, and is a herbaceous annual.