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..
Herbs, mostly hirsute, pubescent or scabrous, with alternate or basal, rarely opposite leaves, and perfect regular 5-parted flowers, in scorpioid cymes, spikes or racemes, or rarely solitary. Calyx inferior, deeply cleft or divided, the sinuses sometimes appendaged. Corolla gamopetalous, funnelform, salverform, campan-ulate, or rotate. Stamens 5, inserted on the tube or base of the corolla, and alternate with its lobes; filaments filiform; anthers ovate, oblong, or linear, mostly versatile, 2-celled, the sacs longitudinally dehiscent. Disk annular or none. Ovary superior, 2-celled, or 1-celled with 2 placentae; styles 2, separate, or partly united; stigmas small, terminal ovules few or numerous, anatropous or amphitropous; Capsule 1-2-celled, mostly loculicidally 2-valved, rarely septicidally or irregularly dehiscent. Seeds oblong, globose, or angular, usually pitted, rugose or reticulated; endosperm fleshy or cartilaginous; embryo small; cotyledons half-terete or plano-convex.
About 17 genera and 175 species, mostly natives of western North America. Styles united below; ovary 1-celled; leaves mostly lobed or dentate.
Corolla-lobes convolute (rarely imbricated) in the bud; placentae dilated. Stamens exserted.
Stamens not exserted.
Sinuses of the calyx appendaged.
Calyx much enlarged in fruit, its sinuses not appendaged.
Corolla-lobes imbricated in the bud; placentae narrow.
Styles distinct to the base; ovary 2-celled; leaves entire.