This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", 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..
Erect or ascending perennial herbs, with mainly basal long-petioled ovate or orbicular leaves, and small paniculate or racemose, white green or purple flowers, on naked or leafy-bracted scapes. Calyx-tube campanulate. often oblique, adnate to the base of the ovary, 5-lobed. Petals small, spatulate, often shorter than the calyx-lobes, entire, inserted on the throat of the calyx. Stamens 5, inserted with the petals. Ovary 1-celled; styles 2, slender. Ovules ∞. Capsule 2-valved, 2-beaked. Seeds minutely hispid or muricate. [Named for Johann Heinrich von Heucher, 1677-1747, a German botanist.]
About 70 species, natives of North America and Mexico. Type species: Heuchera americana L. Flowers regular or nearly so.
Petals with long very slender claws and narrow blades, much exceeding the calyx.
Leaves, at least the larger ones, low rounded lobes.
Petioles villous; calyx-lobes ovate, much shorter than the hypanthium during anthesis.
Petioles puberulent; calyx-lobes broadly ovate, as long as the hypathium during anthesis
or nearly so.
Leaves, at least the larger ones, with prominent angular lobes.
Leaves deeply lobed, the terminal lobe longer than wide.
Leaves not deeply lobed, the terminal lobe broad and short.
Petals with short claws and broad blades, shorter than the calyx or slightly longer.
Petals as long as the calyx or shorter.
Petals decidedly longer than the calyx.
Flowers very irregular.
Stamens slightly exserted or included.
Flowering stem leafless; flowers gibbous below near the base.
Panicle narrow, strict; stamens exserted.
Panicle wide, lax; stamens included.
Flowering stem leafy; flowers not gibbous.