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 in this country is wheatfields. The habit is erect. The lower leaves are ovate to oblong, smooth, blunt, scalloped, toothed. The flowers are creamy-white, 4-6, in whorls, the bracts lance-shaped, acute, small, long and narrow, and blunt-pointed. The calyx-teeth are lance-shaped, acute. The corolla-tube is longer than the calyx. The nutlets are minutely rough. The plant is 4-12 in. high, flowering from July to September, and is a herbaceous annual.
The habitat of this plant is hedges and waste places, and it is found in the neighbourhood of gardens where it is cultivated. The habit is erect. The plant is downy. The stems are stout, with prominent angles, leafy. The leaves are close. The lower leaves are palmate, 5-cleft, with slender long stalks, ovate or rounded to heart-shaped, lobed, cut, toothed, the stem-leaves are stalked, wedge-shaped or inversely ovate to oblong, the lower much divided, the upper 3-fid, entire, 3- (or more) nerved, with acute lobes. The flowers are reddish-white, stalkless, in crowded whorls. The bracts are numerous, large, leaf-like, stalked. There are small bracteoles, awl-like. The calyx-teeth are broadly triangular, sharp. The upper lip of the corolla is straight, hairy, woolly, the helmet nearly flat, the tip spreading, the middle lobe entire. The nutlets are softly hairy at the tip. The plant is 2-3 ft. high, flowering from July to September, and is a herbaceous perennial.
Lamium intermedium, Fr. (=L. molucellifolium, Fr.). - This species is found as a weed of cultivated ground as a rule. The plant is succulent. The radical leaves are stalked, the upper kidney-shaped to heart-shaped, stalkless, scalloped. The flowers are as in the next, in distant whorls below. The calyx-teeth are purple, rigid, longer than the tube, straight, with stiff hairs, spreading. The corolla-tube is cylindrical, equal, with a ring of hairs within, longer than the calyx, the lateral lobes toothed. The nutlets are large, three times as long as broad, with a large, triangular, terminal, oblique space. The plant is in flower from May to September, and is a herbaceous annual.
Lamium hybridum, Vill. ( = L. incisxim, Willd. = L. dissectum, With.). - The habitat of this species is cultivated and waste ground. This plant has been considered a sub-species of L. purpureum, from which it differs in the more deeply scalloped leaves, and bracts wedg-e-shaped below, and erect calyx-teeth, shorter corolla-tube with a scarcely perceptible ring of hairs. The leaves are stalked, heart-shaped, cut to toothed, the upper broadly ovate, crowded, the upper wedge-shaped below. The flowers are reddish, the whorls touching. The calyx-teeth are as long as, or longer than the tube, spreading. The corolla-tube is straight, naked within, equal, cylindrical, with a faint ring of hairs. The nutlets are smooth. The plant is 4-18 in. high, flowering from April to October, and is a herbaceous annual.