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The families of flowering plants

L. Watson and M. J. Dallwitz

Strelitziaceae (K. Schum.) Hutch.

Habit and leaf form. Medium sized to giant herbs, or trees (then unbranched, palmlike). Rhizomatous. Leaves medium-sized to very large; alternate; distichous; petiolate; sheathing. Leaf sheaths tubular to not tubular; with free margins. Leaves simple. Lamina entire (but often tearing or fragmenting along the veins); pinnately veined (pinnate-parallel).

General anatomy. Plants with silica bodies (these spherical in the hypodermis, and as druses adjacent to the vascular bundles).

Leaf anatomy. Epidermis without silica bodies. Stomata present; weakly cyclocytic. Hairs absent. The mesophyll containing mucilage cells (with raphides); containing crystals. The crystals raphides. Foliar vessels absent. Minor leaf veins without phloem transfer cells (Strelitzia).

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

The vessel end-walls scalariform.

Root anatomy. Root xylem with vessels; vessel end-walls scalariform, or scalariform and simple (then mainly scalariform).

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

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in panicles. The ultimate inflorescence units cymose. Inflorescences scapiflorous; terminal, or axillary; thyrses, with one to several lateral, distichously arranged cincinni, each (or only one) of these subtended by a large, stiff, lanceolate or boat-shaped and usually brightly coloured bract; spatheate. Flowers bracteate; very irregular; zygomorphic (with the inner tepals variously specialized); cyclic; pentacyclic. Perigone tube absent.

Perianth of ‘tepals’; 6; joined (the outer members free, the inner joined, the laterals to each other and the median either joined to them basally only, or free); 2 whorled (the median member of the outer whorl abaxial (anterior)); anisomerous; petaloid; different in the two whorls (the members of the inner whorl free or more or less adnate to those of the inner whorl; the two laterals of the inner whorl larger than the median (adaxial, posterior) one, and in Strelitzia these two inner laterals strongly asymmetrical and connivent, forming a large, bilaterally symmetrical arrow-shaped organ that enfolds the filaments and style).

Androecium (5–)6. Androecial members free of the perianth; free of one another; 2 whorled (3+3 or 3+2). Androecium exclusively of fertile stamens, or including staminodes. Staminodes usually 1 (representing the median member of the inner whorl, adjacent to the adaxial ‘petal’); in the same series as the fertile stamens and internal to the fertile stamens. Stamens 6 (Ravenala), or 5; diplostemonous; alterniperianthial; filantherous (the filaments filiform, long). Anthers basifixed (?); dehiscing via longitudinal slits. Microsporogenesis successive. Pollen grains nonaperturate (‘omniaperturate’, almost lacking exine but with a thick intine); 2-celled.

Gynoecium 3 carpelled. Carpels isomerous with the perianth. The pistil 3 celled. Gynoecium syncarpous; synstylovarious, or eu-syncarpous; inferior. Ovary 3 locular. Gynoecium stylate. Styles 1; apical; much longer than the ovary (filiform). Stigmas 1, or 3 (the style terminating in three linear, stigmatic lobes). Placentation axile. Ovules 20–50 per locule (‘many’); arillate; anatropous; 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; ephemeral. Synergids pear-shaped. Endosperm formation nuclear.

Fruit non-fleshy; dehiscent; a capsule. Capsules loculicidal. Seeds endospermic. Perisperm present. Seeds conspicuously hairy (via the aril), or not conspicuously hairy; surrounded by a conspicuous, laciniate-lobed or densely hairy aril. Embryo well differentiated. Cotyledons 1 (massive). Embryo straight. Testa operculate; without phytomelan.

Seedling. Hypocotyl internode absent. Mesocotyl absent. Seedling collar conspicuous. Cotyledon hyperphyll compact; non-assimilatory. Coleoptile present. Seedling cataphylls present. First leaf dorsiventral. Primary root persistent.

Physiology, phytochemistry. Not cyanogenic. Proanthocyanidins present, or absent (Ravenala); in Strelitzia, cyanidin. Flavonols present (Strelitzia), or absent (Ravenala); when present, kaempferol and quercetin. Ellagic acid absent.

Geography, cytology. Paleotropical, Neotropical, and Cape. Sub-tropical to tropical. Central and tropical South America, West Indies, South Africa, Madagascar. X = 7, 8, 11.

Taxonomy. Subclass Monocotyledonae. Dahlgren et al. Superorder Zingiberiflorae; Zingiberales. APG 3 core angiosperms; Superorder Lilianae; commelinid Monocot; Order Zingiberales.

Species 7. Genera 3; Phenakospermum, Ravenala, Strelitzia.

Illustrations. • Technical details: Strelitzia (Thonner). • Technical details of seed (Ravenala). • Strelitzia reginae: Bot. Mag. 119, 1790.

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: 19th October 2016.’.