The families of flowering plants
Alternatively Cannabaceae auctt., Cannabiaceae auctt., Cannabinaceae auctt.
Including Lupulaceae 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 flowers functionally 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.
Perianth sepaline; 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.
Seedling. Germination phanerocotylar.
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. Dahlgrens Superorder Malviflorae; Urticales. Cronquists Subclass Hamamelidae; Urticales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; fabid; Order Rosales.
Species 3. Genera 2; Cannabis, Humulus.
Illustrations. • Technical details: Cannabis, Humulus. • Cannabis sativa: Eng. Bot. 1280, 1868. • Humulus lupulus: Eng. Bot. 1284, 1868. • Humulus lupulus: B. Ent..
Hops and turkies, carps and beer,
Came into England all in a year.
(Quoted by Isaac Walton in The Complete Angler, 1653)
This description is offered for casual browsing only. We strongly advise against extracting comparative information from it. This is much more easily achieved using the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG).
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 19th December 2012. http://delta-intkey.com’.