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.
Dwarf fibrous-rooted herbs with sessile or clasping ovate-lanceolate cauline leaves and solitary or geminate pedunculate pendulous yellow flowers. Perianth-segments free to the base, linear-lanceolate or spathulate, slightly spreading. Fruit capsular, few-seeded. A small genus from North America and the mountains of Northern India. The name is from uvula, said to be applied on account of their medicinal use in diseases of that organ. It has also been explained as referring to the pendent flowers.
1. U. grandiflora. - This species grows about a foot high, and the oblong-ovate slightly hairy leaves are perfoliate. Flowers pale yellow, 1 1/2 to 2 inches long, appearing in May or June. North America.
U. puberula and U. sessilifolia have sessile not-perfoliate leaves and pale yellow or cream-coloured flowers; and U. per-foliata is near grandiflora, but with smaller flowers.