The families of flowering plants

L. Watson and M.J. Dallwitz

Heliconiaceae (Endl.) Nak.

Habit and leaf form. Large, erect herbs (from 75–700cm tall). Perennial; with a basal aggregation of leaves, or without conspicuous aggregations of leaves; cormous. Leaves alternate; distichous; long petiolate; sheathing. Leaf sheaths tubular. Leaves simple. Lamina entire; elliptic or oblong; pinnately veined (with a prominent midrib, from which diverge obliquely the numerous, parallel secondary veins, which arch and merge to form a marginal vein). Leaves eligulate. Lamina margins entire. Leaf development not ‘graminaceous’. Vernation convolute.

General anatomy. Plants with ‘crystal sand’, or without ‘crystal sand’. Plants with silica bodies (rectangular, in associaton with the vascular bundles).

Leaf anatomy. Epidermis without silica bodies. Stomata present; paracytic, or tetracytic. The mesophyll containing mucilage cells (with raphides); containing crystals. The crystals raphides (and/or crystal sand). Foliar vessels absent. Minor leaf veins without phloem transfer cells.

Axial (stem, wood) anatomy. Secondary thickening absent. The axial xylem without vessels.

Root anatomy. Root xylem with vessels; vessel end-walls scalariform.

Reproductive type, pollination. Plants hermaphrodite. Floral nectaries present. Nectar secretion from the gynoecium (via septal nectaries). Pollination ornithophilous.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in panicles. The ultimate inflorescence units cymose (monochasial). Inflorescences scapiflorous, or not scapiflorous; borne on an erect peduncle, consisting of a large, flattened erect or drooping thyrse, often with a conspicuously geniculate axis, each lateral branch subtended by a stiff, usually boat shaped, sometimes quite large and often showy (green, red, orange) bract, the lateral branches consisting of dense monochasial cymes which may be almost concealed in the bract axils; spatheate. Flowers bracteate (the floral bracts smaller and thinner than the cincinnal bracts); very irregular; strongly zygomorphic (the symmetry inverted relative to Costaceae, Musaceae, Strelitziaceae and Zingiberaceae, the the median tepal of the outer whorl being posterior, adaxial). The floral irregularity involving the perianth and involving the androecium. Flowers 3 merous; cyclic. Perigone tube present to absent (the five joined tepals plus the one one more or less free tepal forming a tube, which can widen without bursting when visited by relatively broad-beaked birds).

Perianth of ‘tepals’; 6; joined (the median member of the outer series more or less free from the rest, which are fused to form a five-dentate or five-lobed, boat shaped upper lip); 2 whorled; isomerous; petaloid; similar in the two whorls to different in the two whorls.

Androecium 6. Androecial members free of the perianth; free of one another. Androecium including staminodes. Staminodes 1 (the odd member of the outer series, closing the slit in the perianth tube); petaloid (somewhat), or non-petaloid (then subulate). Stamens 5; reduced in number relative to the adjacent perianth. Anthers basifixed; tetrasporangiate. Microsporogenesis successive. Pollen grains nonaperturate; 2-celled.

Gynoecium 3 carpelled. Carpels isomerous with the perianth. The pistil 3 celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; inferior. Ovary 3 locular. Gynoecium stylate. Styles 1 (often somewhat curved and slightly clavate); apical. Stigmas 1, or 3; wet type; papillate. Placentation basal to axile. Ovules 1 per locule; non-arillate; anatropous; bitegmic; crassinucellate. Embryo-sac development Polygonum-type. Endosperm formation nuclear.

Fruit fleshy; a schizocarp. Mericarps (2–)3; comprising drupelets, or comprising berrylets (?). Fruit 3 seeded. Seeds copiously endospermic. Perisperm present. Seeds triangular. Embryo weakly differentiated (at least when the seed first matures). Cotyledons 1. Embryo straight. Testa operculate (at the micropylar end); without phytomelan; often blue.

Seedling. Hypocotyl internode present (short). Seedling collar conspicuous. Cotyledon hyperphyll compact; non-assimilatory. Coleoptile absent (but with pronounced cotyledon sheath lobes). Seedling cataphylls present. First leaf dorsiventral. Primary root ephemeral.

Physiology, phytochemistry. Not cyanogenic. Proanthocyanidins present.

Geography, cytology. Neotropical. Tropical. Tropical America. X = 12.

Taxonomy. Subclass Monocotyledonae. Dahlgren et al. Superorder Zingiberiflorae; Zingiberales. APG III core angiosperms; Superorder Lilianae; commelinid Monocot. APG IV Order Zingiberales.

Species 80. Genera 1; only genus, Heliconia.

Illustrations. • Le Maout and Decaisne: Heliconia spp.. • Heliconia angustifolia: Lindley. • Heliconia bihai: Lodiges, Bot. Cab. 3 (1818).

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: 5th March 2018.’.