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The families of flowering plants

L. Watson and M.J. Dallwitz

Hypecoaceae (Prantl & Kundig) Barkley

~ Fumariaceae, Papaveraceae.

Habit and leaf form. Low, mostly glabrous, glaucous herbs (branched from the base); non-laticiferous, without coloured juice (but with watery juice which becomes turbid!). Rather dwarf annual; with a basal aggregation of leaves. Leaves alternate; simple, or compound; when ‘compound’, bipinnate, or multiply compound (then multiply pinnatipartite). Lamina when ‘simple’, dissected; much-divided. Leaves exstipulate.

General anatomy. Plants with laticifers, or without laticifers (?).

Leaf anatomy. Hairs present, or absent; unicellular.

Axial (stem, wood) anatomy. Primary vascular tissues probably comprising a ring of bundles (?). Secondary thickening absent, or developing from a conventional cambial ring (?).

Reproductive type, pollination. Fertile flowers hermaphrodite. Plants hermaphrodite. Pollination entomophilous; mechanism conspicuously specialized (the pollen being shed in the bud into pockets in the inner surfaces of the inner petals, which close before the stigma develops and open when pressed by insects, dusting them with pollen).

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in cymes (dichasial). The ultimate inflorescence units cymose. Inflorescences more or less scapiflorous (leafless below); loosely cymose. Flowers bracteate (the bracts pinnatifid); small (usually), or medium-sized; regular; 2 merous (throughout); cyclic. Free hypanthium absent. Hypogynous disk absent (?).

Perianth with distinct calyx and corolla; 6; 3 whorled; isomerous. Calyx 2 (antero-posterior); 1 whorled; polysepalous; neither appendaged nor spurred (and the sepals not lobed); not persistent; open in bud (not enclosing the flower bud). Corolla 4; 2 whorled (the outer pair rhomboid to trilobed, the inner pair deeply trifid with the central segment more or less spathulate, stipitate and fimbriate); polypetalous; usually yellow, or orange.

Androecium 4. Androecial members branched, or unbranched (depending on interpretation of the units); free of the perianth; all equal; free of one another (not diadelphous). Androecium exclusively of fertile stamens. Stamens 4; filantherous. Filaments winged. Anthers dehiscing via longitudinal slits; latrorse; bilocular, or unilocular and bilocular (the median units having been interpreted each as two monothecal units); tetrasporangiate, or bisporangiate and tetrasporangiate; biapiculate. Pollen shed as single grains. Pollen grains aperturate; 2 aperturate (sometimes synaperturate); colpate; 2-celled.

Gynoecium 2 carpelled. Carpels isomerous with the perianth. The pistil 1 celled. Gynoecium syncarpous; synovarious to synstylovarious; superior. Ovary 1 locular. Gynoecium transverse; stylate. Styles 2; partially joined; attenuate from the ovary; apical; much shorter than the ovary. Stigmas 2; dorsal to the carpels, or commissural (?); dry type; papillate; Group II type. Placentation parietal. Ovules in the single cavity 30–100 (‘many’); campylotropous; bitegmic; crassinucellate. Endosperm formation nuclear.

Fruit non-fleshy; dehiscent (sometimes), or lomentaceous (mostly, nodose, divided by late developing transverse septa and breaking up into 1-seeded sections); when not lomentaceous, a siliqua (with a replum). Capsules when dehiscent, valvular (bivalved, dehiscing acroptetally). Seeds copiously endospermic. Endosperm oily. Embryo well differentiated (but small). Cotyledons 2.

Physiology, phytochemistry. Not cyanogenic.

Geography, cytology. Holarctic. Temperate (warm). Mediterranean to central Asia and China.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Malviflorae; Urticales. Cronquist’s Subclass Magnoliidae; Papaverales. APG III core angiosperms; peripheral eudicot; Superorder Ranunculanae. APG IV Order Ranunculales (as a synonym of Papaveraceae).

Species 15. Genera 1; only genus, Hypecoum.

General remarks. Differing fairly unimpressively from Papaveraceae in habit and inflorescence form, the extent of carpellary fusion, and supposedly in the well differentiated seed embryo. No anatomical information located.

Illustrations. • Le Maout and Decaisne: Hypecoum procumbens. • Hypecoum erectum, H. leptocarpum, H. zhukarnum: Fl. of China 7 (2008).

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.’.