The families of flowering plants.
Habit and leaf form. Herbs. Perennial; rhizomatous (the rhizome short and thick, the stem unbranched, with only two or three leaves). Mesophytic. Leaves alternate; petiolate; non-sheathing; simple. Lamina dissected; palmatifid; palmately veined; cross-venulate; cordate. Leaves exstipulate. Lamina margins serrate, or dentate.
Stem anatomy. Primary vascular tissue in two or more rings of bundles (two rings). Medullary bundles present. Secondary thickening developing from a conventional cambial ring (in the rhizome). Vessel end-walls scalariform, or reticulately perforated. Sieve-tube plastids S-type.
Reproductive type, pollination. Plants hermaphrodite.
Inflorescence, floral, fruit and seed morphology. Flowers solitary; terminal; large; regular; partially acyclic. The androecium acyclic. Free hypanthium present. Hypogynous disk absent.
Perianth sepaline, or petaline, or of ‘tepals’ (usually described as having petaloid sepals and no corolla); 4; free; (if considered ‘of tepals’) petaloid; persistent. Calyx 4; polysepalous; persistent.
Androecium350–500 (very numerous). Androecial members branched; maturing centrifugally; free of the perianth; free of one another; spiralled. Androecium exclusively of fertile stamens. Stamens 20–200 (very numerous); polystemonous; filantherous. Anthers tetrasporangiate. Pollen grains aperturate; 3 aperturate.
Gynoecium usually 2 carpelled (opposite the outer perianth members). The pistil 2 celled (below). Gynoecium apocarpous to syncarpous; semicarpous (the carpels united in the lower third); superior. Carpel 15–20 ovuled (‘many’). Placentation marginal. Ovary usually 2 locular (below). Ovules bitegmic; crassinucellate.
Fruit non-fleshy. The fruiting carpel dehiscent; a follicle (dehiscing along both dorsal and vental sutures). Seeds endospermic; winged (and compressed). Embryo well differentiated. Cotyledons 2.
Physiology, biochemistry. Not cyanogenic. Alkaloids absent.
Geography, cytology. Holarctic. Temperate. Japan. N = 10.
Taxonomy.Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Ranunculiflorae; Ranunculales. Cronquist’s Subclass Magnoliidae; Ranunculales. APG 3 core angiosperms; peripheral eudicot; Superorder Ranunculanae; Order Ranunculales (as a synonym of Ranunculaceae).
Species 1. Genera 1; only genus, Glaucidium.
General remarks. See Tamura 1972, Bot. Mag. Tokyo 85, 40–.