This section is from the book "British Wild Flowers - In Their Natural Haunts Vol2-4", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
The charming Rosebay, known in our gardens as well as the fields, is found in the Temperate and Arctic parts of Europe at the present day (there are no earlier records), in N. and W. Asia, as far east as the Himalayas, and in America. In Great Britain it has not been found in Cornwall, but in the rest of the Peninsula, and the whole of the Channel and Thames provinces. In Anglia it is not found in West Suffolk and Cambridge nor in Hunts or Northants, but throughout the Severn province; in Wales only in Glamorgan, Brecon, Cardigan, Merioneth, Carnarvon, Denbigh, Anglesea, and Flint. It is not found in S. Lincs or Notts in the Trent province, but throughout the Mersey and Humber provinces except in S.E. Yorks, and throughout the Tyne and Lakes provinces. In Scotland it is found throughout the W. Lowlands, except in Wigtown and Renfrew; in the S. Lowlands, except in Peebles, Selkirk, Haddington; the whole of E. Highlands, West Highlands, except Mid Ebudes; and in the North Highlands everywhere except in E. Sutherland. It is found in the Highlands at 2700 ft., and in N. and E. Ireland.
The Rosebay is a woodland plant, delighting in a rocky upland clearing, but growing as frequently on the loose rubble of a quarry side or wherever natural scars and crags are exposed, in the neighbourhood of woods. One of our handsomest wild flowers, held also in admiration in the garden, Rosebay is tall, erect, much branched, with numerous long, narrow, lance-shaped, veined, scattered leaves, alternate, with a white midrib and whitish under side, the margin minutely and finely toothed. The stems are downy. The bracts or leaf-like organs are like the leaves connected with the flower. The second Latin name explains the shape of the leaves.
The first Latin name refers to the inferior position of the ovary below the perianth, the flowers apparently resting on a lobe or pod (later). The flowers are purple, unequal or irregular, in a spike. The calyx is spreading and free, the stigma is bent.
The plant is 3-4 ft. high. It flowers in July and August. It is perennial, increasing by division, and often cultivated.
Sprengel, as long ago as 1790, showed that the flowers, which open soon after sunrise, are proterandrous, i.e. the anthers ripen first, though in some the stigma is ripe first, and self-pollination would occur if insects did not visit them.
The flowers are large and purple, in a tall, conspicuous spike, and are much visited by insects. Honey is secreted by the green, fleshy upper surface of the ovary, and is easily reached by insects, but protected from the rain, as it then bends over. The expanded, flattened lower ends of the filaments or anther-stalks form a hollow cone, which encloses the base of the style and the honey surrounding" it, protecting the latter; and where the style issues at the apex of the cone hairs prevent the entrance of rain, while insects can gain access through the anther-stalks.
In young flowers pollen covers the stamens above, and they project, but the style is short and bent over, with the stigmas folded together; but in older flowers the empty stamens are bent down and turn outward, and the style is longer and projects forward, with 4 stigmas outspread and recurved taking the place of the stamens. The insects can alight, suck, and collect pollen easily. Cross-pollination is secured, and self-pollination is impossible. The flowers are visited by Apis, Bombus, Sphecodes, Nomada, Cerceris, Crabro, Ammophila, Tenthredo, Empis, Syrphus, Ino statices.
The seeds are provided with a tuft of hairs, which aid them in their dispersal by the wind after the pods or long narrow capsules have split open to release them. The pods split from above downwards between the valves and along the centre, the seeds being attached to the axis. They are very small, oblong, brown, with a tuft of long, white, silky hairs at the upper end, which serve as a parachute.
Photo. B. Hanley - Rosebay (epilobium Angustifolium, L.)
Rosebay is a rock-loving plant, growing on barren stony hillsides, or it may be a sand-loving plant, growing on a sand soil, such as the sandy beds of the Lias or Keuper Marl.
The fungus which infests the Rosebay is called Melampsora pustulata.
The Rosebay is galled by Hormomyia fasciata, Laverna decorella. The beetles Cercus bipustulatus, Haltica lythri, H. cleracea, H. pusilla; the Hymenopterous insect Tenthredo colon; the Lepidoptera, The Mouse, Amphipyra tragopogonis, Small Phoenix Moth, Cidaria sila-ceata, Laverna substrigillata; the Homoptera Cidadula dahlbomii, Aphalara nebulosa; and the Heteropterous insect Dicyphus Epilobii feed on the Rosebay in one way or another.
Epilobium, Gesner, is from the Greek epi, on, lobos, a pod, because the flower apparently grows upon a lobe, and the second Latin name refers to the narrow leaves.
This plant is known by the name of Rosebay, Bay-willow, Blood Vine, Blooming Sally, Cat's Eyes, Persian Willow, Tame Withy, Blooming, French, and Rosebay Willow, Bay Willow Herb.
Rosebay was called Tame Withy because it was frequently grown in gardens, and because of its willow-like leaves.
This handsome plant is called Rosebay because the leaves are like laurel and the flowers purple like a rose. It was named Blood Vine because the whole plant has a red appearance. In Ireland, "Sally" in the name Blooming Sally is a corruption for the Latin Salix.
The Rosebay finds a place in the garden, the established plant differing from the wild one. It used to be employed to adulterate tea, and was boiled also as a vegetable, the young shoots being eaten as asparagus. They are fermented to make beer in Kamschatka, and made especially intoxicating with a toadstool, Agaricus muscarius, the Fly Agaric. The down has been mixed with cotton and fur to make stockings and other clothing.
Essential Specific Characters: 118. Epilobium angustifolium, L. - Stem tall, erect, terete, leaves scattered, lanceolate, acute, alternate, flowers rose-pink, in a raceme, irregular, stamens and style bending ultimately.