Family Portulacaceae
Portulacaceae Juss.Including Metabletaceae Dulac, Lewisieae (Lewisiaceae) Hook. & Arn., Montiaceae Dum., Spaetalumeae Wyeth & Nuttall, Talinaceae DoweldExcluding Hectorellaceae Habit and leaf form. Shrubs and herbs. ‘Normal’ plants. Plants succulent (often), or non-succulent. Helophytic to xerophytic. Leaves alternate, or opposite; when alternate, spiral; fleshy (often), or ‘herbaceous’; petiolate to sessile; non-sheathing; simple. Lamina entire; linear, or lanceolate, or oblanceolate, or ovate, or obovate; pinnately veined, or one-veined; cross-venulate. Leaves stipulate, or exstipulate (Claytonia). Stipules intrapetiolar; scaly (or sometimes, as in Portulaca, represented by axillary hairs). Lamina margins entire. Leaves without a persistent basal meristem. General anatomy. Plants with ‘crystal sand’ (Calandrinia), or without ‘crystal sand’. Leaf anatomy. Stomata anomocytic, or paracytic. The mesophyll usually containing mucilage cells. Minor leaf veins without phloem transfer cells (Calandrina, Lewisia, Montia). Stem anatomy. Nodes unilacunar. Primary vascular tissue comprising a ring of bundles (usually), or in a cylinder, without separate bundles; centrifugal. Internal phloem dubiously present (e.g. in Montia), or absent. Secondary thickening absent, or developing from a conventional cambial ring. ‘Included’ phloem absent. Xylem with libriform fibres; with vessels. Vessel end-walls simple. Sieve-tube plastids P-type; type III (a). Reproductive type, pollination. Unisexual flowers absent. Plants hermaphrodite. Pollination entomophilous. Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; in cymes. The ultimate inflorescence unit cymose. Inflorescences usually cymes, often dichasial or tending to cincinni. Flowers bracteolate (if the ‘sepals’ are interpreted as bracteoles); small, or medium-sized; regular to somewhat irregular; cyclic; tetracyclic. Free hypanthium present to absent. Hypogynous disk present. Perianth with distinct calyx and corolla, or sepaline (the latter if the ostensible ‘calyx’ is interpreted as ‘bracteoles’, whereupon the ‘corolla’ becomes a petaloid calyx); 7; 2–3 whorled; anisomerous. Calyx 2; 1–2 whorled; polysepalous, or gamosepalous (the members sometimes united basally); persistent; imbricate (the upper member overlapped). Corolla (if not interpreted as calyx) (2–)5(–18); 1 whorled; polypetalous, or gamopetalous (sometimes basally connate). Corolla lobes markedly longer than the tube. Corolla imbricate; regular; white, or yellow, or pink, or purple (often satiny). Androecium 5, or 10, or 4–100 (i.e. to ‘many’). Androecial members branched (bundled, when ‘many’), or unbranched; free of the perianth, or adnate (to the corolla base); free of one another, or coherent; when coherent 1 adelphous, or 2–7 adelphous (?); 1 whorled, or 2 whorled. Androecium exclusively of fertile stamens. Stamens 3, or 4, or 5, or 10, or 6–50; isomerous with the perianth, or diplostemonous to polystemonous; when 5, alternisepalous (opposite the petals). Anthers dehiscing via longitudinal slits; introrse; tetrasporangiate. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral. Anther wall initially with one middle layer; of the ‘monocot’ type. Tapetum glandular. Pollen grains aperturate; 3–6 aperturate, or 13–30 aperturate (or more?); colpate, or foraminate, or rugate (then pantocolpate, sometimes irregularly); 3-celled (in Portulaca and Talinum). Gynoecium (2–)3(–9) carpelled. Carpels reduced in number relative to the perianth. The pistil 1 celled. Gynoecium syncarpous; synovarious, or synstylovarious; superior, or partly inferior (Portulaca). Ovary 1 locular. Styles 1, or 3(–9); apical. Stigmas dry type; papillate; Group II type. Placentation basal, or free central. Ovules in the single cavity 2–100 (to ‘many’); anatropous to amphitropous; bitegmic; crassinucellate. Outer integument not contributing to the micropyle. Embryo-sac development Polygonum-type. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids hooked (and sometimes with filiform apparatus). Endosperm formation nuclear. Embryogeny caryophyllad, or solanad. Fruit non-fleshy; dehiscent (usually), or indehiscent; a capsule, or capsular-indehiscent. Capsules circumscissile, or valvular. Fruit elastically dehiscent (sometimes), or passively dehiscent. Seeds non-endospermic. Perisperm present. Seeds with starch. Embryo well differentiated. Cotyledons 2(–4). Embryo achlorophyllous (2 species of Portulaca); curved. The radicle dorsal. Seedling. Germination phanerocotylar. Physiology, biochemistry. Not cyanogenic. Alkaloids absent, or absent. Iridoids not detected. Proanthocyanidins present, or absent; when present, cyanidin. Flavonols present, or absent; kaempferol. Ellagic acid absent (2 genera, 2 species). Betalains present, or absent. Saponins/sapogenins present, or absent. Plants often accumulating free oxalates. C4 and CAM (and C4/CAM intermediates?). C4 physiology recorded directly in Anacampseros, Portulaca (plus with very weak CAM). CAM recorded directly in Anacampseros, Calandrinia, Ceraria, Portulacaria, Talinum. Anatomy C4 type (Portulaca, Trianthema), or non-C4 type (Talinum). Geography, cytology. Temperate to tropical. Cosmopolitan, except for frigid zones. X = 4–42 (or more). Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Caryophylliflorae; Caryophyllales. Cronquist’s Subclass Caryophyllidae; Caryophyllales. APG 3 core angiosperms; core eudicot; Superorder Caryophyllanae; Order Caryophyllales. Species 580. Genera about 20; Amphipetalum, Anacampseros, Baitaria, Calandrinia, Calyptridium, Calyptrotheca, Ceraria, Cistanthe, Claytonia, Grahamia, Lenzia, Lewisia, Montia, Portulaca, Rumicastrum, Schreiteria, Silvaea, Talinella, Talinopsis, Talinum. Economic uses, etc. A few cultivated ornamentals (Portulaca grandiflora, Talinum, Lewisia and Calandrina spp.), and Portulaca oleracea constitutes a potherb and salad green. Illustrations. |
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