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..
Shrubs or low woody herbs, with alternate or opposite simple leaves, and solitary racemose clustered or paniculate flowers. Flowers regular, generally perfect. Sepals 3 or 5, persistent, when 5 the 2 exterior ones smaller and bract-like, the 3 inner convolute. Petals 5 or 3, or sometimes wanting, fugacious. Stamens 00, hypogynous. Ovary 1, sessile, 1-several-celled; ovules orthotropous, stalked; style simple; stigma entire or 3-lobed. Capsule dehiscent by valves. Seeds several or numerous; embryo slender, straight or curved; endosperm starchy or fleshy.
Eight genera and about 160 species, mostly natives of the northern hemisphere.
Petals 5, yellow, fugacious, or wanting.
Leaves broad, lanceolate or oblong; style short.
Leaves subulate or scale-like, imbricated; style long.
Petals 3, not yellow, persistent; flowers minute; style none.