Papaveraceae Juss.

Scientific Description

Common name. Poppy Family.

Habit and leaf form. Herbs (mostly), or trees to shrubs (a few shrubs or small treelets); laticiferous, or with coloured juice (usually, the juice milky, yellow, or red), or non-laticiferous and without coloured juice (e.g. Eschscholtzia, Platystemon with watery juice). Annual, or perennial; plants with neither basal nor terminal concentrations of leaves. The treelets pachycaul. Mesophytic. Leaves alternate (usually, though the floral leaves are sometimes opposite or whorled), or whorled (ostensibly, in Platystemon); spiral; petiolate to sessile; non-sheathing; simple. Leaf blades dissected (usually), or entire; usually pinnatifid (lobed or dissected), or much-divided (e.g. bipinnatisect); pinnately veined; cross-venulate. Leaves without stipules; without a persistent basal meristem. Leaf anatomy. Hydathodes present (occasionally), or absent. Stem anatomy. Nodes unilacunar, or tri-lacunar. Secondary thickening absent (commonly), or developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous.

Inflorescence and flower features. Flowers solitary (mostly), or aggregated in ‘inflorescences’; in cymes and in racemes. The terminal inflorescence unit cymose, or racemose. Inflorescences terminal; racemes or dichasia. Flowers medium-sized, or large; operculate (calyptrate), or not operculate; odourless; regular, or somewhat irregular. The floral asymmetry involving the perianth (when manifest). Flowers cyclic; tetracyclic to pentacyclic to polycyclic. Floral receptacle developing an androphore, or developing a gynophore, or with neither androphore nor gynophore. Free hypanthium absent (usually), or present (Platystemon). Hypogynous disk absent. Perianth with distinct calyx and corolla (usually), or sepaline (the corolla lacking in Macleaya); 6(–10); 1 -whorled, or 3 -whorled, or 4 -whorled; anisomerous (calyx whorl reduced relative to corolla whorls). Calyx 2(–4); 1 -whorled; polysepalous, or gamosepalous (sometimes basally connate, sometimes coherent into an operculum); calyptrate, or not calyptrate; imbricate; unequal but not bilabiate, or regular (usually rather asymmetrical); not persistent (caducous). Corolla 4, or 6, or 8, or 12, or 16; 2 -whorled (often 2+2 or 3+3), or 3 -whorled; polypetalous; imbricate and crumpled in bud; regular; yellow, or orange, or red, or pink, or blue; not spurred. Androecium 4–6 (Meconella), or 16–200 (usually ‘many’). Androecial sequence determinable, or not determinable. Androecial members usually maturing centripetally; free of the perianth; free of one another; 3–15 -whorled (generally indefinite in 2- or 3-merous, regularly alternating whorls). Androecium exclusively of fertile stamens. Stamens 4–6 (rarely), or 16–60; isomerous with the perianth (rarely), or diplostemonous to polystemonous. Anthers basifixed; non-versatile; dehiscing via longitudinal slits; tetrasporangiate. Gynoecium 2(–100) carpelled (to ‘many’). The pistil 1 celled, or 2–20 celled. Carpels isomerous with the perianth, or increased in number relative to the perianth. Gynoecium syncarpous; semicarpous (Platystemon), or eu-syncarpous (the stigmas often connate to form a discoid roof on the ovary); superior. Ovary unilocular, or plurilocular; 1 locular, or 2–20 locular (by intrusion of the placentas). Locules secondarily divided by ‘false septa’, or without ‘false septa’. Gynoecium when G2, transverse; non-stylate, or stylate. Stigmas as many as the placentas; dorsal to the carpels, or commissural, or dorsal to the carpels and commissural; often combined into a peltate structure; dry type; papillate; Group II type. Placentation when unilocular parietal (usually), or basal (Bocconia); when plurilocular, axile. Ovules in the single cavity when unilocular 1 (Bocconia), or 2–100 (usually ‘many’); when plurilocular, 2–50 per locule (few to ‘many’); horizontal, or ascending; with superior or lateral raphe; arillate, or non-arillate; anatropous, or campylotropous, or amphitropous.

Fruit and seed features. Fruit non-fleshy; more or less an aggregate (Platystemon), or not an aggregate; dehiscent (usually), or indehiscent (rarely), or a schizocarp (Platystemon); a capsule (usually), or a silicula, or a siliqua, or a nut (rarely). Capsules poricidal, or septicidal, or valvular. Seeds copiously endospermic. Endosperm oily. Embryo rudimentary at the time of seed release (sometimes), or weakly differentiated. Cotyledons 2. Embryo achlorophyllous (7/8). Seedling. Germination phanerocotylar, or cryptocotylar.

Physiology, biochemistry. Aluminium accumulation not found. Photosynthetic pathway: C₃.

Geography, cytology, number of species. World distribution: mainly North temperate, but also in Iceland, Central America and West Indies, South Africa and Eastern Australia. X = (5-)6, 7, 8, 11, 19. 200 species.

Economic uses, etc. Unripe capsules of Papaver somniferum supply commercial opium, and numerous species from Papaver, Meconopsis, Argemone, etc. are cultivated as ornamentals.