Family Nelumbonaceae
Nelumbonaceae Dum.Habit and leaf form. Aquatic herbs; laticiferous (with articulated laticifers). With neither basal nor terminal aggregations of leaves; rhizomatous. Hydrophytic; rooted. Leaves emergent, or floating. Heterophyllous (in the sense that the leaf primordia arise in threes: one giving rise to a scale-leaf on the underside of the rhizome, which at first envelopes the terminal bud, while the second develops into an upper scale leaf which enwraps the petiole base of the large laminate leaf). Leaves medium-sized, or large; with the peculiar arrangement described; foliage leaves long petiolate; simple; peltate. Lamina entire; palmately veined. Leaves stipulate. Stipules intrapetiolar; concrescent; ochreate. Leaves without a persistent basal meristem. Leaf anatomy. Stomata present; anomocytic. Lamina with secretory cavities. Secretory cavities containing latex. The mesophyll without sclerenchymatous idioblasts. Vessels absent. Stem anatomy. Secretory cavities present; with latex. Primary vascular tissue in scattered bundles. Secondary thickening absent. Xylem presumably with tracheids; without vessels. Sieve-tube plastids S-type. Root anatomy. Root xylem with vessels. Reproductive type, pollination. Plants hermaphrodite. Pollination entomophilous; via beetles. Inflorescence, floral, fruit and seed morphology. Flowers solitary; bracteate (via an upper scale leaf); ebracteolate; large; regular; acyclic. The perianth acyclic and the androecium acyclic, or the perianth acyclic, the androecium acyclic, and the gynoecium acyclic (the gynoecium in ‘more or less distinct’ whorls). Free hypanthium absent. Perianth with distinct calyx and corolla (the outer several members perhaps interpretable as K), or sequentially intergrading from sepals to petals; about 22–30; free. Calyx (if so interpreted) 2–8; polysepalous; not persistent; imbricate. Corolla (if the inner members so interpreted) 18–28; polypetalous; imbricate; yellow, or red to pink. Androecium about 200–400. Androecial members maturing centripetally; free of the perianth; free of one another; spiralled. Androecium exclusively of fertile stamens. Stamens about 200–400; filantherous. Anthers adnate; non-versatile; dehiscing via longitudinal slits; introrse and latrorse; tetrasporangiate; appendaged. The anther appendages apical (as a flat or clavate extension of the connective). Endothecium developing fibrous thickenings. Microsporogenesis simultaneous. Tapetum glandular. Pollen shed as single grains. Pollen grains aperturate; 3 aperturate; colpate; 3-celled. Gynoecium 12–40 carpelled; apocarpous; eu-apocarpous; superior. Carpel apically stigmatic (the stigma annular-dilated); 1(–2) ovuled. Placentation apical to marginal (ventral). Ovules pendulous; apotropous; with dorsal raphe; non-arillate; anatropous; bitegmic; crassinucellate. Outer integument not contributing to the micropyle. Embryo-sac development Polygonum-type. Antipodal cells formed; 3; not proliferating; very ephemeral. Synergids pear-shaped. Endosperm formation cellular. Embryogeny asterad. Fruit non-fleshy (but the individual carpels sunken in the spongy receptacle); an aggregate. The fruiting carpels not coalescing (ultimately — free within the receptacle, released separately as it disintegrates), or coalescing into a secondary syncarp (i.e. this structure being not unreasonably described as such). The fruiting carpel indehiscent; nucular. Fruit loosely enclosed with its neighbours in the spongy, swollen receptacle, finally released by decay; 1 seeded. Seeds non-endospermic. Perisperm absent. Cotyledons 2 (connate, and sheathing the plumule). Embryo chlorophyllous (1/2). Physiology, biochemistry. Not cyanogenic. Alkaloids present. Iridoids not detected. Proanthocyanidins present. Ellagic acid absent. Saponins/sapogenins absent. Geography, cytology. Sub-tropical to tropical. Eastern U.S.A. to Colombia, and warm Asia to Northeast Australia. X = 16. Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Magnoliiflorae; Nelumbonales. Cronquist’s Subclass Magnoliidae; Nymphaeales. APG 3 core angiosperms; peripheral eudicot; Superorder Proteanae; Order Proteales. Species 2. Genera 1; only genus, Nelumbo. Economic uses, etc. N. pentapetala rhizomes provided starchy food for American Indians. Illustrations. |
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