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 or shrubs (sometimes trees in tropical regions) with alternate mostly palmately-veined leaves. Stipules small, deciduous. Flowers regular, perfect, often large, rarely dioecious or polygamous. Sepals 5 (rarely 3 or 4),more or less united, usually valvate; calyx often bracted at the base. Petals 5, hypogynous, convolute, often contorted. Stamens ∞, hypogynous, monadelphous, forming a central column around the pistil, united with the bases of the petals; anthers I-celled. Ovary several-celled, entire or lobed; styles united below, distinct above, and generally projecting beyond the stamen-column, mostly as many as the cells of the ovary; ovules 1 or several in each cavity. Fruit capsular (rarely a berry), several-celled, the carpels falling away entire or else loculicidally dehiscent. Seeds reniform, globose or obovoid; embryo curved; cotyledons large, plicate or condu-plicate; endosperm little, or copious.
About 45 genera and 900 species, widely distributed in tropical and temperate regions. Stamen-column anther-bearing at the summit; carpels in a circle around a central axis.
Involucels of 6-9 bractlets.
Involucels of 1-3 bractlets, or none.
Stigmas linear, on the inner side of the style-branches.
Carpels beakless; petals obcordate.
Carpels beaked; petals truncate.
Stigmas capitate, terminal.
Involucels of 3 bractlets.
Carpels septate between the seeds.
Stamen-column anther-bearing below the entire or 5-toothed summit; fruit a loculicidal capsule.