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..
Perennial or biennial herbs, with large lobed pinnatifid or pinnately divided leaves, and rather large, white blue or purple flowers, in terminal or lateral peduncled more or less scorpioid cymes. Calyx deeply 5-parted, the segments lanceolate or subulate, the sinuses naked or appendaged. Corolla tubular-campanulate or campanulate, 5-lobed, the lobes convolute in the bud, each with a linear appendage within, which extends to the base of the corolla and is incurved into a groove. Stamens 5, exserted; filaments pilose below or at the base; anthers linear or oblong, versatile. Ovary 1-celled, hispid-pubescent; placentae fleshy, dilated so as to nearly fill the cavity, free from the ovary-wall except at the top and bottom, each enclosing 2 ovules; styles united nearly to the summit. Capsule 2-valved. Seeds 1-4, globose-obovoid. [Greek, water-leaf, referring to the supposed cavity for water in each leaf.]
About \2 species, natives of North America. Type species: Hydrophyllum virginianum L. Leaves, at least the lower, pinnatifid or pinnately divided.
Calyx not appendaged in the sinuses or scarcely so. Plant sparingly pubescent; leaf-segments acute.
1. H. virginianum.
Plant villous-hirsute; leaf-segments blunt.
2. H. macrophyllum.
Calyx with a reflexed appendage in each sinus.
3. H. appendiculatum.
Leaves palmately 5-9 lobed.
4. H. canadense.