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This interesting and beautiful woodbine is a hybrid between L. caprifolium and L. etrusca, with both of which it is often confused. It has most resemblance to L. caprifolium in growth and foliage; young stems purple, glabrous. The uppermost pairs of leaves unite into a cup, as in L. caprifolium, but the lower ones differ in being more pointed. Flowers fragrant, in whorls not confined (as in L. caprifolium) to the axils of the connate leaves, but with several other whorls above them springing from the axils of small bracts. Corolla 2 in. long, yellow more or less suffused with reddish purple, the tube slender, usually glandular, downy outside, the two lips giving a diameter of 1 to 11⁄2 in.
The origin of this lovely hybrid is not known, but it existed in the time of Linnaeus, who confused it with L. caprifolium. According to Rehder, it is very rare in the wild, but has been found in S. and S.E. Europe, although even there possibly as an escape from cultivation. It is a very effective climber, the terminal part of the shoot often branching and forming a panicle over 1 ft long and 8 in. through. It received an Award of Garden Merit in 1955.
This hybrid was in cultivation in 1730 and reputed to grow wild in N. America. Philip Miller seems to have doubted the correctness of this belief, so it is the more the pity that he should have adopted for it the epithet americanum. The fallacy was encouraged by Pursh, who, in his Flora Americae Septentrionalis (1814), listed this honeysuckle as an American native. Some European botanists of that time identified it with L. virginiana Marsh., which was, in fact, L. sempervirens. This explains how Loudon, who grew this hybrid as L. grata Ait., could confidently assert that it was an American species that grew wild in Virginia and Carolina.
The essential difference between this hybrid and L. caprifolium is given in the first paragraph. Another difference is that in L. caprifolium the bracteoles subtending the individual flowers are very small or absent, whereas in L. × americana they are present and about half as long as the ovary (in L. etrusca, the other parent, they are about equal to the ovary). The rarity of this hybrid in the wild is probably due to the fact that the two species, even when they occur in the same general area, occupy different habitats, L. etrusca being essentially a constituent of the Mediterranean type of vegetation and L. caprifolium of deciduous woodland.
The flowering time of L. × americana, not given in the description, is June to September or even until the first frosts, though the main flowering is over by autumn. It is very vigorous and hardy.