This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol3", 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..
Twining woody vines (some exotic species nearly erect shrubs), with opposite entire deciduous leaves, and small yellow greenish or white flowers in terminal and axillary compound cymes. Calyx small, deeply. 5-parted, glandular within, the segments narrow. Corolla funnelform or salverform, the tube nearly cylindric, expanded above, the lobes convolute, more or less twisted. Stamens included, or short exserted; anthers sagittate, acuminate, connivent around the stigma and slightly adherent to it. Disk of 5 glandular lobes. Ovary of 2 carpels; ovules numerous in each carpel; style slender, its apex thickened below the narrow ring of the ovoid stigma. Follicles much elongated, slender. Seeds linear or oblong, not beaked, long-comose at the apex. [Greek, neck-seed, but the seed is not beaked.]
About 6 species, natives of eastern Asia and North America. Type species: Trachelospermum jasminoides Lemaire, of eastern Asia. The following is the only known North American species.
A high-climbing vine, the stems 1/2' in diameter or more, the twigs pubescent or glabrous. Leaves thin, ovate, oval or lanceolate, acuminate or acute at the apex, narrowed or rarely rounded at the base, 1 1/2-3' long, 1'-2' wide; petioles 2"-4" long; peduncles slender, shorter than the leaves; pedicels and branches of the cyme bracteolate at the base; flowers yellow or cream-color, 4"-5" long; lobes of the corolla ovate, spreading, shorter than the tube; follicles very slender, 5'-9' long, scarcely 2" thick; many-seeded.