Excluding Tetramelaceae
Habit and leaf form. Tall, glabrous herbs (with the habit of Cannabis). Perennial. Leaves alternate; petiolate; non-sheathing; compound; pinnate. Lamina pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins dentate. Domatia recorded; represented by pockets.
Leaf anatomy. Stomata present; anomocytic.
Lamina dorsiventral. The mesophyll with sclerencymatous idioblasts (H-shaped, in Octomeles), or without sclerenchymatous idioblasts. Minor leaf veins without phloem transfer cells.
Stem anatomy. Cork cambium present; initially superficial. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. `Included' phloem absent. Xylem with libriform fibres. Vessel end-walls simple. Vessels without vestured pits. Wood not storied; parenchyma paratracheal.
Reproductive type, pollination. Dioecious, or androdioecious, or polygamomonoecious. Gynoecium of male flowers absent. Anemophilous.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in `inflorescences'; in fascicles. Inflorescences crowded fascicles on long, leafy branches.
Perianth sepaline; 3-9. Calyx 3-9 (male flowers), or 3-8 (female and hermaphrodite flowers); polysepalous; members unequal; persistent.
Androecium 3-5 (in hermaphrodite flowers), or 8-25 (in male flowers). Androecial members free of the perianth; free of one another. Androecium exclusively of fertile stamens (or hermaphrodite flowers sometimes with some imperfect stamens?). Stamens 8-25 (male flowers), or 3-5 (hermaphrodite flowers); filantherous (the filaments short). Anthers dorsifixed; dehiscing via longitudinal slits; extrorse; tetrasporangiate. Pollen grains aperturate; 3 - aperturate; colporate; 2-celled.
Gynoecium 3-5; syncarpous; synovarious (open at the apex); inferior (ribbed). Ovary 1 locular. Epigynous disk absent. Gynoecium stylate. Styles 3-5 (each deeply bifid). Stigmas dry type; papillate; Group II type. Placentation parietal. Ovules in the single cavity 30-100 (`many'); anatropous; bitegmic; tenuinucellate. Outer integument contributing to the micropyle. Embryo-sac development Allium-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; persistent. Synergids pear-shaped. Endosperm formation nuclear. Embryogeny onagrad.
Fruit non-fleshy; dehiscent; a capsule (membranous). Capsules opening apically between the persistent styles. Fruit 30-100 seeded (`many seeded'). Seeds more or less non-endospermic. Embryo well differentiated (but small). Cotyledons 2 (oily). Embryo straight. Testa coarsely reticulate.
Seedling. Germination phanerocotylar.
Physiology, biochemistry. Not cyanogenic. Proanthocyanidins absent. Flavonols present; kaempferol and quercetin. Ellagic acid absent. Aluminium accumulation not found.
Geography, cytology. Holarctic. Temperate to tropical. Dry Western Eurasia, dry North America. N = 11.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren's Superorder Violiflorae; Violales. Cronquist's Subclass Dilleniidae; Violales. Takhtajan's Subclass Dilleniidae; Dillenianae; Begoniales. Species 2. Genera 1; only genus, Datisca.
Illustrations. datis456.gif
