Family Strelitziaceae
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 (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 calcium oxalate crystals. The mesophyll crystals raphides. Minor leaf veins without phloem transfer cells (Strelitzia). Vessels absent. Stem anatomy. Secondary thickening absent. Xylem with vessels, or without vessels. Vessel end-walls scalariform. Root anatomy. Root xylem with vessels; vessel end-walls scalariform, or scalariform and simple (then mainly scalariform). Reproductive type, pollination. Unisexual flowers absent. 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 unit 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, biochemistry. 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. |
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