This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Glabrous twining woody vines; leaves opposite, or rarely ternate, their bases connected by a stipular line, the very small stipules deciduous; flowers large, yellow, in axillary and terminal nearly sessile cymes, the pedicels scaly-bracteolate. Calyx deeply 5-parted, the segments dry, imbricated. Corolla funnelform, with 5 broad lobes imbricated in the bud.
Stamens 5, inserted on the tube of the corolla; anthers linear-oblong. Ovary oblong, 2-celled; style slender or filiform, 4-cleft, the lobes stigmatic along the inner side; ovules numerous in each cavity, on linear placentae. Capsule elliptic, flattened contrary to the partition, septicidally dehiscent, the valves boat-shaped, 2-cleft at the summit; seeds several in each cell, flattened, winged. [From the Italian Gelsomino, the Jessamine.]
Two known species, the following typical one of the southeastern United States, the other of eastern Asia.
Stem slender, climbing or trailing, sometimes 200 long. Leaves lanceolate, oblong-lanceolate or ovate-lanceolate, entire, short-petioled, persistent, evergreen, 1 1/2'-3' long, 5"-12" wide; cymes 1-6-flowered; pedicels short; bractlets several, dry, oblong or lanceolate, l"-2" long; flowers dimorphous; sepals oblong, obtuse; corolla bright yellow, l'-l 1/2' long; stigmas in one form short and anthers exserted, in the other form longer and anthers included; capsule flat, channeled on both sides, 4"-7" long, cuspidate; seeds very flat, broadly winged at the summit.