The families of flowering plants.
AlternativelyCannabaceae auctt., Cannabiaceae auctt., Cannabinaceae auctt.
IncludingLupulaceae Link, Strobiliaceae Dulac
Habit and leaf form. Herbs, or lianas; laticiferous, or with coloured juice, or non-laticiferous and without coloured juice; resinous, or not resinous. Annual, or perennial. Self supporting (Cannabis), or climbing (Humulus); when climbing, stem twiners; Humulus twining clockwise. Mesophytic. Leaves alternate, or opposite; petiolate; non-sheathing; not gland-dotted; aromatic; simple, or compound; when compound, palmate. Lamina when simple, dissected, or entire; when lobed, palmatifid; palmately veined; cross-venulate. Leaves stipulate. Stipules intrapetiolar; free of one another; persistent. Leaves without a persistent basal meristem.
General anatomy. Plants with laticifers (unsegmented, unbranched — the contents resinous in Cannabis, colourless in Humulus). The laticifers in leaves, in stems, and in the fruits.
Leaf anatomy. Stomata anomocytic.
Lamina dorsiventral. Cystoliths very commonly present. Minor leaf veins without phloem transfer cells (Humulus).
Stem anatomy. Cork cambium present; initially superficial. Secondary thickening developing from a conventional cambial ring. Xylem with libriform fibres; with vessels. Vessel end-walls simple. Vessels without vestured pits. Sieve-tube plastids S-type (with starch).
Reproductive type, pollination. Fertile flowersfunctionally male, or functionally female, or functionally male and functionally female. Plants dioecious, or monoecious (rarely). Gynoecium of male flowers absent. Pollination anemophilous.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’. The ultimate inflorescence unit cymose. Inflorescences generally condensed-spicate. Flowers bracteate; bracteolate; regular; 5 merous; cyclic.
Perianthsepaline; 5; free (male), or joined (female); 1 whorled. Calyx 5; polysepalous (male), or partially gamosepalous (female); regular; persistent; imbricate.
Androecium 5 (in male flowers). Androecial members free of the perianth; all equal; free of one another. Androecium exclusively of fertile stamens. Stamens 5; oppositisepalous; erect in bud. Anthers dorsifixed; dehiscing via longitudinal slits; tetrasporangiate. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral. Anther wall initially with more than one middle layer. Tapetum glandular. Pollen grains aperturate; 3 aperturate (usually), or 2 aperturate, or 4 aperturate, or 6 aperturate; porate; 2-celled.
Gynoecium 2 carpelled. The pistil 1 celled. Gynoecium syncarpous; synstylovarious;superior. Ovary 1 locular. Gynoecium non-stylate, or stylate (the style very short). Styles 1; apical. Stigmas 2 (long); dry type; papillate; Group II type. Placentation apical. Ovules in the single cavity 1; pendulous; non-arillate; anatropous; bitegmic; crassinucellate. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids shortly pear-shaped. Endosperm formation nuclear. Embryogeny onagrad.
Fruit non-fleshy; indehiscent; a nut. Seeds endospermic. Endosperm oily. Seeds with starch. Cotyledons 2. Embryo curved (Cannabis), or coiled (Humulus). The radicle dorsal.
Physiology, biochemistry. Not cyanogenic. Alkaloids present. Iridoids not detected. Proanthocyanidins present (Humulus), or absent (Cannabis); cyanidin and delphinidin (Humulus). Flavonols present; kaempferol, or kaempferol, quercetin, and myricetin. Ellagic acid absent (both genera). Saponins/sapogenins absent. C3. C3 physiology recorded directly in Cannabis.
Geography, cytology. Temperate. North temperate. X = 8, 10.
Taxonomy.Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Malviflorae; Urticales. Cronquist’s Subclass Hamamelidae; Urticales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; fabid; Order Rosales.
Species 3. Genera 2; Cannabis, Humulus.
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