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The families of flowering plants.                                                                                                                                                                

Velloziaceae Endl.

                        

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Habit and leaf form. ‘Arborescent’, or shrubs, or herbs (the stem simple or ostensibly dichotomously branched, covered with persistent leaf sheaths); resinous. Perennial (with adventitous roots at the aerial nodes, emerging through the old leaf bases). More or less xerophytic. Leaves alternate; spiral (the young ones crowded at the branch tips); sessile; sheathing. Leaf sheaths with free margins. Leaves simple. Lamina entire; linear; parallel-veined. Lamina margins entire, or dentate (spinulose).

General anatomy. Accumulated starch other than exclusively ‘pteridophyte type’.

Leaf anatomy. Stomata present; mainly confined to one surface (abaxial, in longitudinal grooves); doubly paracytic (usually), or tetracytic.

Lamina dorsiventral; without secretory cavities. The mesophyll containing calcium oxalate crystals, or without calcium oxalate crystals (?). The mesophyll crystals raphides (in at least some genera). Minor leaf veins without phloem transfer cells (Vellozia). Vessels present (usually), or absent; end-walls scalariform.

Stem anatomy. Primary vascular tissue in scattered bundles. Secondary thickening absent. Xylem with vessels (seemingly rarely), or without vessels. Vessel end-walls scalariform.

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

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

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’ (few-flowered); usually ostensibly terminal. Inflorescences not scapiflorous (the ‘scape’ carrying the generally solitary flower probably representing a pedicel); ostensibly terminal; espatheate. Flowers regular; basically 3 merous; cyclic. Perigone tube present, or absent.

Perianthof ‘tepals’; 6; free, or joined; 2 whorled (3+3); isomerous; petaloid (and often with separate or fused ‘coronal appendages’, more or less fused with the tepals, external to and usually adnate to the stamens, probably representing filament lobes, cf. Amaryllidaceae); similar in the two whorls, or different in the two whorls; white, or yellow, or purple, or violet, or blue (usually brightly coloured).

Androecium 6, or 18–66 (Vellozia). Androecial members unbranched, or branched (in Vellozia, by division of the stamen initials); adnate (to the perianth tube, or to the tepals and/or to the coronal appendages); free of one another, or coherent (in Vellozia, in groups); or the stamen groups 2 whorled. Androecium exclusively of fertile stamens (?). Stamens6, or 18–66 (Vellozia); isomerous with the perianth, or polystemonous; laminar, or petaloid, or filantherous. Filaments appendiculate (being variously expanded, sometimes contributing a corona, sometimes with ventral basal appendages, sometimes flat and apically bifid), or not appendiculate. Anthers dorsifixed (peltate or medifixed), or basifixed; dehiscing via longitudinal slits; latrorse to introrse (usually), or extrorse (very rarely). Microsporogenesis successive. Tapetum glandular. Pollen shed in aggregates (rarely), or shed as single grains; when in aggregates, in tetrads (Vellozia only). Pollen grains aperturate (usually), or nonaperturate; when aperturate, 1 aperturate; sulcate; probably 3-celled (Dahlgren et al. 1985).

Gynoecium 3 carpelled. Carpels isomerous with the perianth. The pistil 3 celled.Gynoecium syncarpous; synstylovarious to eu-syncarpous; inferior.Ovary 3 locular (variously pubescent, sometimes with glands or scales). Gynoecium stylate. Styles 1; apical. Stigmas 1, or 3; 1 lobed, or 3 lobed; when single clavate, or capitate. Placentation axile (the placentas variously sessile, laminar or stalked, often globose or bibrachiate). Ovules30–50 per locule (or more — ‘many’); horizontal; arillate (at least sometimes with a funicular obturator), or non-arillate (?); anatropous; bitegmic; tenuinucellate. Embryo-sac development Polygonum-type. Endosperm formation helobial.

Fruit non-fleshy; dehiscent; a capsule. Capsules splitting irregularly (or apically), or loculicidal. Seeds copiously endospermic; small. Seeds with starch. Cotyledons 1. Testa without phytomelan;red (the outer integument containing phlobaphene).

Seedling.Hypocotyl internode present (short). Seedling collar not conspicuous. Cotyledon hyperphyll compact; non-assimilatory. Coleoptile absent. Seedling cataphylls absent. First leaf dorsiventral. Primary root ephemeral.

Physiology, biochemistry. Not cyanogenic. Proanthocyanidins absent. Flavonols present; quercetin, or kaempferol and quercetin. Ellagic acid absent. Saponins/sapogenins absent.

Geography, cytology. Paleotropical and Neotropical. Sub-tropical to tropical. Tropical South America, Africa and Madagascar, Arabia.

Taxonomy.Subclass Monocotyledonae. Dahlgren et al. Superorder Bromeliiflorae; Velloziales. APG 3 core angiosperms; Superorder Lilianae; non-commelinid Monocot; Order Pandanales.

Species about 270. Genera 7; Acanthochlamys, Aylethonia, Barbacenia,Barbaceniopsis, Burlemarxia, Vellozia, Xerophyta.

 Illustrations:

  • Technical details: Barbacenia.
  • Technical details: Barbacenia (Thonner). 
  • Vellozia (Chittenden).
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