The families of flowering plants
Habit and leaf form. Arborescent, or shrubs, or herbs (with the stems simple or ostensibly dichotomously branched, these thin but the upper parts thickly covered with old, fibrous leaf sheaths, and the lower parts with adventitious roots); resinous. Plants autotrophic. Perennial (adventitous roots at the aerial nodes emerging through the old leaf bases); with a basal aggregation of leaves, or with terminal aggregations of leaves (rosetted, Aloë-like). More or less xerophytic (with sponge-like capacity to absorb water, chiefly on rocky places or dry campos). Leaves alternate; spiral (the young ones crowded at the branch tips); xerophytic, often pungent; sessile; sheathing. Leaf sheaths with free margins. Leaves simple. Lamina entire; acicular, or linear; parallel-veined. Lamina margins entire, or dentate (spinulose).
Leaf anatomy. The leaf lamina dorsiventral. Stomata present; mainly confined to one surface (abaxial, in longitudinal grooves); doubly paracytic (usually), or tetracytic. Lamina without secretory cavities. The mesophyll containing crystals, or without crystals (?). The crystals raphides (in at least some genera). Foliar vessels present (usually), or absent; with scalariform end-walls. Minor leaf veins without phloem transfer cells (Vellozia).
Axial (stem, wood) anatomy. Primary vascular tissues consisting of scattered bundles. Secondary thickening absent. The axial xylem with vessels (seemingly rarely), or without vessels.
The vessel end-walls scalariform.
Root anatomy. Root xylem with vessels; vessel end-walls simple.
Reproductive type, pollination. 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. Flowers regular; basically 3 merous; cyclic. Perigone tube present, or absent.
Perianth of tepals; 6; free, or joined; 2 whorled (3+3); isomerous; petaloid (and often with separate or fused coronal appendages, these 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 (3+3), or 18–66 (then bundled, 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); when cohering, 6 adelphous; 2 whorled. Androecium exclusively of fertile stamens (?). Stamens 6, or 18–66 (Vellozia); isomerous with the perianth, or diplostemonous, 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). Ovules 30–50 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 septicidal (according to Airy Shaw), 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, phytochemistry. Accumulated starch other than exclusively pteridophyte type. Not cyanogenic. Saponins/sapogenins absent. Proanthocyanidins absent. Flavonols present; quercetin, or kaempferol and quercetin. Ellagic acid 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. • Vellozia abietina: Martius, Nova Gen. et Spec. Pl. Brasiliensium (1824). • Vellozia candida: Bot. Mag. 91 (1865). • Barbacenia brasiliensis, as B. bicolor: Martius, Nova Gen. et Spec. Pl. Brasiliensium (1824). • Le Maout and Decaisne: Barbacenia. • Barbacenia aequatorialis: Thonner. • Xerophyta alba, as Vellozia: Hook. Ic. Pl. 24 (1895). • Vellozia (Chittenden).
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: 24th October 2017. delta-intkey.com/angio’.