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The families of flowering plants

L. Watson and M.J. Dallwitz

Papaveraceae Juss.

Including Chelidoniaceae Nak., Chymaceae Dulac, Eschscholziaceae (Ernst) A.C. Smith, Platystemonaceae (Ernst) A.C. Smith; excluding Fumariaceae, Hypecoaceae, Pteridophyllaceae.

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, without coloured juice (e.g. Eschscholtzia, Platystemon with watery juice). Annual, or perennial; without conspicuous aggregations 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. Lamina dissected (usually), or entire; usually pinnatifid (lobed or dissected), or much-divided (e.g. bipinnatisect); pinnately veined (mostly), or palmately veined (e.g., Eomecon); cross-venulate. Leaves exstipulate; leaf development not ‘graminaceous’.

General anatomy. Plants with laticifers (these articulated, anastomosing or not), or without laticifers. The laticifers in leaves, in stems, in roots, in flowers, and in the fruits.

Leaf anatomy. The leaf lamina usually dorsiventral. Hydathodes present (occasionally), or absent. Stomata mainly confined to one surface, or on both surfaces; anomocytic. Hairs present, or absent (scanty, unicellular, uniseriate, biseriate or multiseriate, sometimes shaggy); eglandular; unicellular, or multicellular. Multicellular hairs uniseriate, or multiseriate; branched, or simple. Minor leaf veins without phloem transfer cells (Meconopsis).

Axial (stem, wood) anatomy. Young stems commonly with hollow internodes. Nodes unilacunar, or tri-lacunar. Primary vascular tissues comprising a ring of bundles (mostly), or comprising two or more rings of bundles (occasionally, e.g. often in Papaver); collateral. Cortical bundles absent. Medullary bundles absent. Secondary thickening absent (commonly), or developing from a conventional cambial ring. Primary medullary rays wide.

The wood in woody forms (Bocconia, Dendromecon, Romneya) semi-ring porous (Dendromecon), or diffuse porous. The vessels small, or medium; in radial multiples, or clustered, or in tangential arcs. The vessel end-walls horizontal, or oblique; simple. The vessels with spiral thickening. The axial xylem with libriform fibres; without septate fibres. The fibres without spiral thickening. The parenchyma paratracheal (vasicentric to sparse); wood not storied. Tyloses absent.

Reproductive type, pollination. Fertile flowers hermaphrodite. Plants hermaphrodite; not viviparous. Floral nectaries absent. Pollination anemophilous (e.g., Bocconia, Macleaya), or entomophilous (mostly).

Inflorescence, floral, fruit and seed morphology. Flowers solitary (mostly), or aggregated in ‘inflorescences’; when aggregated, in cymes and in racemes. The ultimate inflorescence units cymose, or racemose. Inflorescences terminal; racemes or dichasia. Flowers medium-sized, or large; calyptrate, or not calyptrate; odourless; regular, or somewhat irregular. The floral irregularity 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; isomerous (nearly always), or anisomerous (Sanguinaria). Calyx 2(–4); 1 whorled; polysepalous, or gamosepalous (sometimes basally connate, sometimes coherent into an operculum); unequal but not bilabiate, or regular (usually rather asymmetrical); basally appendaged (sepals sometimes lobed), or neither appendaged nor spurred; not persistent (caducous); calyptrate, or not calyptrate; imbricate. 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 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. 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, or initially with more than one middle layer. Tapetum glandular. Pollen grains aperturate (usually?), or nonaperturate (e.g., some Meconopsis species); (2–)3 aperturate, or 4 aperturate, or 6–8 aperturate, or 9(–15) aperturate; colpate (mostly, tricolpate, rarely slightly colporoidate), or foraminate, or rugate; 2-celled (in 4 genera).

Gynoecium 2(–100) carpelled (to ‘many’). Carpels isomerous with the perianth, or increased in number relative to the perianth. The pistil 1–20 celled. Gynoecium syncarpous; semicarpous (Platystemon), or eu-syncarpous (usually, the stigmas often connate to form a discoid roof on the ovary); superior. Ovary 1 locular, or 2–20 locular (by intrusion of the placentas). Locules secondarily divided by ‘false septa’ (then spuriously bilocular), or without ‘false septa’. Gynoecium when G2, transverse. Ovary sessile, or stipitate. Gynoecium non-stylate, or stylate. Styles when gynoecium stylate, 1; attenuate from the ovary; apical. Stylar canal present. 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, or parietal (Romneya). Ovules in the single cavity when unilocular 1 (Bocconia), or 2–100 (usually ‘many’); when plurilocular, 2–50 per locule (few to ‘many’); funicled; horizontal, or ascending; with ventral raphe; collateral, or superposed, or over the carpel surface, or biseriate; arillate, or non-arillate; anatropous, or campylotropous, or amphitropous (seemingly mostly anatropous or subcampylotropous); 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; persistent. Synergids hooked (with filiform apparatus). Endosperm formation nuclear. Embryogeny solanad (or irregular).

Fruit non-fleshy; more or less an aggregate (Platystemon), or not an aggregate; dehiscent (usually), or indehiscent (rarely), or a schizocarp (Platystemon). Mericarps in Platystemon, 2–20(–30). Fruit a capsule (usually), or a silicula, or a siliqua, or a nut (rarely). Capsules poricidal, or septicidal, or valvular (then dehiscence basipetal or acropetal). Fruit elastically dehiscent, or passively dehiscent. Dispersal unit the seed, or the mericarp, or the fruit. Dispersal by explosive xerochastic dehiscence, censer action in windy conditions, or passive fall; commonly involving ants when elaiosomes present; rarely (Arctomecon) the fruits fall and tummble in the wind. Fruit 1–100 seeded (i.e. to ‘many’). Seeds copiously endospermic. Endosperm oily. Seeds small. Embryo rudimentary at the time of seed release (sometimes), or weakly differentiated. Cotyledons 2. Embryo achlorophyllous (7/8). Testa non-operculate; smooth.

Seedling. Germination phanerocotylar, or cryptocotylar.

Physiology, phytochemistry. C3. C3 physiology recorded directly in Argemone, Macleaya. Cyanogenic, or not cyanogenic. Cynogenic constituents tyrosine-derived. Alkaloids present (nearly always), or absent. Berberine present (at least in Argemone), or absent. Arbutin absent. Iridoids not detected. Proanthocyanidins absent. Flavonols present; kaempferol, or quercetin, or kaempferol and quercetin. Ellagic acid absent (6 species, 6 genera). Aluminium accumulation not found. Sieve-tube plastids S-type.

Geography, cytology. Holarctic, Paleotropical, Neotropical, Cape, and Australian. Frigid zone to sub-tropical. Mainly North temperate, but also in Iceland, Central America and West Indies, South Africa and Eastern Australia. X = (5-)6, 7, 8, 11, 19.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Ranunculiflorae; Papaverales. Cronquist’s Subclass Magnoliidae; Papaverales. APG III core angiosperms; peripheral eudicot; Superorder Ranunculanae. APG IV Order Ranunculales.

Species 200. Genera 23; Arctomecon, Argemone, Bocconia, Canbya, Chelidonium, Dendromecon, Dicranostigma, Eomecon, Eschscholzia, Glaucium, Hunnemannia, Hylomecon, Macleaya, Meconella, Meconopsis, Papaver, Platystemon, Platystigma, Roemeria, Romneya, Sanguinaria, Stylomecon, Stylophorum.

General remarks. The data compiled for this package exhibit differences between Fumariaceae and Papaveraceae involving seven morphological characters; however, the taxonomic justification for retaining the separate families is reduced if the current descriptions significantly under-estimate intra-familial variation.

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


. . . Not poppy, nor mandragora,
Nor all the drowsy syrups of the world,
Shall ever med’cine thee to that sweet sleep
Which thou owed’st yesterday
(‘Othello’, iii., 3 - ‘owed’st = ‘owned’)

Corn poppies, that in crimson dwell,
Called Head-aches, from their sickly smell
(John Clare, quoted by Ann Pratt, ‘Wild Flowers’ (1857)

On her cheek an autumn flush,
Deeply ripen’d; - such a blush
In the midst of brown was born,
Like red poppies grown with corn
(Thomas Hood, ‘Ruth’)

History of the encoded description. This description improved by Una Smith, July 1998.

Illustrations. • Le Maout and Decaisne: Papaver rhoeas. • Le Maout and Decaisne: Glaucium, Meconopsis Platystemon. • Le Maout and Decaisne: Chelidonium, Eschscholzia, Roemeria. • Argemone grandiflora: Bot. Reg. 1264, 1829. • Chelidonium majus (J. E. Sowerby, 1861). • Chelidonium majus: Eng. Bot. 67, 1863. • Glaucium flavum (as G. luteum): Eng. Bot. 66, 1863. • Meconopsis nipalensis: Hooker’s Illustrations of Himalayan plants (1855). • Meconopsis cambrica: Eng. Bot. 63, 1863. • Papaver argemone and P. dubium (as P. lamottei): Eng. Bot. 59 and 61, 1863. • Papaver hybridum: Eng. Bot. 62, 1863. • Papaver orientale: Bot. Mag., 1788. • Papaver somniferum var. somniferum (as P. hortense) and P. rhoeas: Eng. Bot. 57 and 58, 1863. • Platystemon californicus: as P. californicum, Bot. Reg. 1679, 1835. • Platystigma lineare: Bot. Reg. 1954, 1837. • Roemeria hybrida: Eng. Bot. 64, 1863. • Glaucium, Roemeria, Papaver (B. Ent. compilation). • Papaver, Chelidonium (B. Ent. compilation).

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or 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). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 15th April 2018.’.