The families of flowering plants
Including Devauxiaceae Dum.; excluding Hydatellaceae.
Habit and leaf form. Grass- or mosslike herbs. Annual, or perennial; with a basal aggregation of leaves (when annual), or without conspicuous aggregations of leaves. Leaves alternate; spiral; sessile; sheathing. Leaf sheaths with free margins. Leaves borne edgewise to the stem (rarely), or normally orientated; simple. Lamina entire; setaceous, or linear; parallel-veined. Leaves ligulate, or eligulate; leaf development graminaceous.
General anatomy. Plants with silica bodies (?), or without silica bodies. Chlorenchyma without peg cells.
Leaf anatomy. Epidermis without differentiation into long and short cells; containing silica bodies (? Gaimardia), or without silica bodies. Stomata present; paracytic. Guard-cells grass type (according to the text of Dahlgren et al. (1985), though their illustration of Pseudalepyrum depicts them otherwise). The mesophyll without crystals. Foliar vessels present; with scalariform end-walls.
Axial (stem, wood) anatomy. Secondary thickening absent.
The vessel end-walls scalariform.
Root anatomy. Root xylem with vessels (sought only in Pseudalepyrum); vessel end-walls scalariform.
Reproductive type, pollination. Plants monoecious, or andromonoecious, or polygamomonoecious. Gynoecium of male flowers pistillodial. Floral nectaries absent (nectaries absent). Pollination anemophilous.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in inflorescences; in spikelets (each pseudanthium being borne within two or more glumelike bracts). The ultimate inflorescence units cymose. Inflorescences pseudanthial (as currently interpreted, the bisexual and female heads of Centrolepis and Gaimardia being seen as unisexual and bisexual aggregations of flowers, each of the latter being reduced to either one stamen or one carpel). Flowers bracteate; bracteolate (the flowers sometimes with thin subtending bractlets), or ebracteolate; small.
Androecium 1 (constituting the male flower, as here interpreted); exclusively of fertile stamens. Stamens 1. Anthers dorsifixed; versatile; dehiscing via longitudinal slits; bisporangiate. Microsporogenesis successive. Pollen grains aperturate; 1 aperturate; ulcerate. The ulcus without an operculum (and with no vestiges of an operculum); without an annulus. Interapertural exine scrobiculate. Interapertural interstitium granulate. Pollen grains 2-celled.
Gynoecium 1 carpelled (constituting the female flower). The pistil 1 celled. Gynoecium monomerous; of one carpel; superior. Carpel 1 ovuled. Placentation apical. Ovary stipitate. Ovules pendulous; non-arillate; orthotropous; bitegmic; tenuinucellate. Outer integument contributing to the micropyle. Embryo-sac development Polygonum-type (the Poaceae variant). Antipodal cells formed; 3; not proliferating. Synergids non-haustorial. Hypostase present. Endosperm formation helobial. Embryogeny onagrad.
Fruit non-fleshy. The fruiting carpel dehiscent; a follicle (tiny). Gynoecia of adjoining flowers combining to form a multiple fruit (the collective fruits capsule-like). Dispersal unit the seed. Seeds copiously endospermic. Endosperm not oily (starchy). Perisperm absent. Seeds with starch. Embryo rudimentary at the time of seed release (minute, obconical). Testa without phytomelan; thin.
Seedling. Hypocotyl internode absent. Seedling collar not conspicuous. Cotyledon hyperphyll elongated; assimilatory; more or less circular in t.s. Coleoptile absent. Seedling cataphylls absent. First leaf centric. Primary root ephemeral.
Physiology, phytochemistry. Accumulated starch other than exclusively pteridophyte type. Not cyanogenic. Aluminium accumulation demonstrated (Centrolepis). Sieve-tube plastids P-type; type II.
Geography, cytology. Temperate to tropical. Southeast Asia and Australasia. X = 10–13.
Taxonomy. Subclass Monocotyledonae. Dahlgren et al. Superorder Commeliniflorae; Poales. APG 3 core angiosperms; Superorder Lilianae; commelinid Monocot; Order Poales.
Species 40. Genera 5; Aphelia, Brizula, Centrolepis, Gaimardia, Pseudalepyrum.
Illustrations. • Aphelia and Centrolepis (including ‘Alepyrum’), with Trithuria (Hydatellaceae): Hooker, Fl. Tasmaniae (1860). • Technical details: Centrolepis (Lindley). • Technical details: Centrolepis, Aphelia.
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: 13th March 2017. delta-intkey.com/angio’.