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 ditches and river-banks, watery places. The plant has the willow-herb habit, or more or less that of a rosette below, with erect stem. There are autumnal stolons, with more or less stalkless, or stalked, rosettes of leaves. The root is fibrous. The stem is downy, round in section, branched above, or more or less simple. The leaves are stalkless, more or less alternate, lance-shaped, with a rounded base, toothed. The radical leaves have short stalks. The flowers are small, with erect, ovoid buds, rose-purple, numerous. The sepals are lance-shaped. The lobes of the stigma are short and not turned back. The capsule is nearly smooth or downy. The seeds are tubercular, inversely ovate to oblong, rounded below. The plant is 1-3 ft. in height, flowering in July and August, and is a herbaceous perennial.
Epilobium collinum, C. Gmel. - This species is a doubtful one, and has been referred to E. mon-tanum. It was found in Scotland.
The habitat of this species is wet places. The habit is as in the last. There are dense, stalkless rosettes. The plant is downy above. The stem has 2 or 4 raised lines, or is round, and is erect, much-branched, rough, and strong. The leaves are stalkless, those below the branches opposite, sometimes shortly - stalked, running down the stem. They are strap-shaped, linear to oblong, ovate, toothed, shining below. The buds are erect, acute. The flowers are purplish-rose colour, or lilac, erect. The pods are 2-4 in. long. The seeds are oblong to inversely ovate, tubercular. The plant is 1-2 ft. in height, and flowers in July and August, being a herbaceous perennial.
The habitat of this species is damp places. The habit is as in the last, which it resembles except in the shorter capsule and foliage. The autumn stolons have few distant pairs of opposite leaves. The leaves are ovate to lance-shaped, tapered from a rounded base, and are stalkless, remotely toothed. The lower leaves are oblong, blunt, not shining above. The buds are erect. The capsule is more or less erect or spreading. The seeds are oblong to inversely ovate. The plant flowers in July and August, and is a herbaceous perennial.
Epilobium Lamyi, F. Schultz. - The habitat of this plant is woods and roadsides. The plant forms dense rosettes. The leaves are lance-shaped, finely or coarsely toothed, rounded below, sometimes with a short leaf-stalk, bluish-green, acute, closely downy. The flowers are larger than in E. tetragonum. The buds are erect. The plant is 1-3 ft. in height. It flowers in July and August, and is a herbaceous perennial.
The habitat of this plant is bogs, ditches. The habit is as in the other members of the group. The summer stolons are subterranean, slender, scaly, with scaly buds in autumn, and are long-jointed, with very small leaves, which end in bulbs in autumn, becoming detached. The stem has a cordlike base, roots near the base, and is round in section, with two lines of felt. The leaves are not stalked, and are lance-shaped, nearly all opposite, limp, spreading, with few teeth, with a narrow, blunt tip. The leaves are wedge-shaped at the base. The flowers are in a raceme, nodding at the top, rose or lilac. The buds are blunt, nodding.
The sepals are lance-shaped. The capsule is downy. The seeds are spindle-shaped, narrower, narrow and acute below, with the testa prolonged. The plant is 6-24 in. in height. It flowers in July and August, and is a herbaceous perennial.