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..
Herbs, with milky or colored sap, and alternate leaves or the upper rarely opposite. Stipules none. Flowers solitary or in clusters, perfect, regular. Sepals 2 (rarely 3 or 4), caducous. Petals 4-6 or rarely more, imbricated, often wrinkled, deciduous. Stamens mostly numerous, hypogynous, distinct; filaments filiform; anthers innate, longitudinally dehiscent. Ovary 1, many-ovuled, mainly 1-celled, with parietal placentae; style short; stigma simple or divided; ovules anatropous. Fruit a capsule, dehiscent by a pore, or by valves. Seeds mostly numerous; embryo small at the base of fleshy or oily endosperm.
About 23 genera and 115 species, widely distributed, most abundant in the north temperate zone.
Pod dehiscent at the top, or only to the middle.
Leaves not spiny-toothed.
Pod dehiscent to the base.
Flowers white; petals 8-16; juice red.
Flowers and juice yellow; petals 4.
Capsule oblong or short-linear, bristly.
Capsule long-linear, rough, tipped with a dilated stigma.
Capsule linear, smooth, tipped with a short subulate style and minute stigma.