The families of flowering plants.
Habit and leaf form. Herbs and shrubs (and sub-shrubs); bearing essential oils, or without essential oils; resinous (commonly), or not resinous (?). ‘Normal’ plants, or switch-plants. Leaves well developed, or much reduced (sometimes to scales). Mesophytic, or xerophytic (especially in sunny places on chalk or sand). Leaves opposite (usually), or whorled (sometimes), or alternate (rarely); flat, or rolled (often ‘ericoid’); ‘herbaceous’, or leathery, or membranous; petiolate to sessile; non-sheathing; aromatic, or without marked odour; simple. Lamina entire; one-veined, or pinnately veined, or palmately veined. Leaves stipulate, or exstipulate (when the leaf amplexicaul). Stipules intrapetiolar; free of one another; leafy. Lamina margins flat, or revolute.
Leaf anatomy. Mucilaginous epidermis present, or absent. Stomata present; mainly confined to one surface, or on both surfaces; anomocytic. Hairs present; eglandular, or glandular; unicellular, or multicellular. Complex hairs commonly present; commonly peltate, or stellate, or capitate.
Lamina dorsiventral to centric. Cystoliths commonly present. Minor leaf veins with phloem transfer cells (Helianthemum), or without phloem transfer cells (Cistus).
Stem anatomy. Young stems cylindrical, or tetragonal. Cork cambium present; initially deep-seated (rarely), or superficial. Nodes unilacunar. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. ‘Included’ phloem absent. Xylem with vessels. Vessel end-walls simple. Vessels with vestured pits. Wood parenchyma absent or rare.
Reproductive type, pollination. Unisexual flowers absent. Plants hermaphrodite.
Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; when aggregated, in cymes. The ultimate inflorescence unit cymose. Inflorescences terminal, or axillary; various forms of cymes. Flowersbracteolate (the two bracteoles not to be confused with the two outer sepals, which may be smaller than the other three); medium-sized to large (showy); regular; cyclic (sometimes), or partially acyclic. Usually the androecium acyclic. Floral receptacle developing an androphore, or developing a gynophore (the stamens borne on or outside the well developed hypogynous disk). Free hypanthium absent. Hypogynous disk present; extrastaminal to intrastaminal.
Perianth with distinct calyx and corolla (ignoring cleistogamous flowers); (6–)10; 2 whorled, or 3 whorled. Calyx 3, or 5 (the two outer members often smaller and narrower); 1 whorled, or 2 whorled; polysepalous, or partially gamosepalous (the two outer members sometimes adnate to the inner members); usually persistent; with at least the three inner members contorted. Corolla 5 (usually), or 3 (in Lechea, missing from cleistogamous flowers); 1 whorled; polypetalous; contorted (nearly always, in the opposite direction to the sepals), or imbricate (in Lechea); regular; white, or yellow, or red; deciduous (usually caducous). Petals scarcely clawed, or sessile.
Androecium (3–)15–100 (usually ‘many’). Androecial members branched, or unbranched (?); when many, maturing centrifugally; free of the perianth; free of one another. Androecium exclusively of fertile stamens (usually), or including staminodes (Fumana). Staminodes of Fumana external to the fertile stamens. Stamens (3–)15–100 (usually ‘many’); isomerous with the perianth to polystemonous. Anthers dehiscing via longitudinal slits; introrse; tetrasporangiate. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral, or decussate. Anther wall initially with one middle layer. Tapetum glandular. Pollen grains aperturate; (2–)3(–5) aperturate; colporate; 2-celled.
Gynoecium 3 carpelled, or 5–10 carpelled. Carpels reduced in number relative to the perianth to increased in number relative to the perianth. The pistil 1–10 celled. Gynoecium syncarpous; synstylovarious, or eu-syncarpous;superior. Ovary 1 locular (but sometimes incompletely 3–10 locular, by intrusion and fusion of the placentas, e.g. in Cistus). The ‘odd’ carpel anterior. Ovary sessile. Gynoecium non-stylate to stylate. Styles 1; apical. Stigmas 1 (usually, minute to large and capitate, or discoid and lobed), or 3; dry type; papillate; Group II type. Placentation parietal. Ovules in the single cavity 15–100 (usually ‘many’ — two to many on each placenta); funicled; ascending; non-arillate; orthotropous (usually), or anatropous (e.g. Fumana); bitegmic; crassinucellate. Outer integument contributing to the micropyle. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids pear-shaped, or hooked (with filiform apparatus). Endosperm formation nuclear. Embryogeny solanad.
Fruit non-fleshy; dehiscent; a capsule. Capsules loculicidal, or valvular (opening from the top downwards). Seeds endospermic. Endosperm not oily. Seeds usually small; wingless. Seeds with starch. Embryo well differentiated. Cotyledons 2. Embryo chlorophyllous (1/1); curved (almost straight in Lechea), or bent, or coiled.
Seedling. Germination phanerocotylar.
Physiology, biochemistry. Not cyanogenic. Alkaloids absent (5 species). Iridoids not detected. Proanthocyanidins present; cyanidin and delphinidin, or delphinidin. Flavonols present; kaempferol, quercetin, and myricetin. Ellagic acid absent (2 genera). Saponins/sapogenins present, or absent. Aluminium accumulation not found. C3. C3 physiology recorded directly in Helianthemum, Hudsonia. Anatomy non-C4 type (Helianthemum).
Geography, cytology. Holarctic and Neotropical. Temperate (mainly), or sub-tropical to tropical (a few). Mostly North temperate, especially Mediterranean, but a few in Central and South America. X = 5–11.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Malviflorae; Malvales. Cronquist’s Subclass Dilleniidae; Violales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; malvid; Order Malvales.
Species 200. Genera 9; Atlanthemum, Cistus, (Crocanthemum), Fumana, Halimimum, Helianthemum, Hudsonia,Lechea, Therocistus, Turberaria.
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