This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Herbs or undershrubs, often climbing or trailing. Leaves alternate, rarely opposite, exstipulate, simple, and usually entire. Flowers hermaphrodite, irregular, solitary, spicate or racemose. Sepals 5, free, imbricated, the two innermost larger, petaloid. Petals 3 or 5, hypogynous; the 2 outer free, or united with the hooded lower one forming a tube split at the posterior base, the 2 inner equal or smaller or absent. Stamens 8; filaments connate in a tube, and united with the petals below. Capsule 2-celled, compressed, dehiscing loculicidally. Seeds pendulous, hairy or glabrous, often strophiolate, with or without albumen.