|Abstract||Mostly perennial, paludose, grass-like herbs with fibrous roots; stembase very rarely thickened, often profusely producing shoots. Leaves basal, distichous on each shoot, ensiform, linear or filiform, sometimes twisted; sheaths with a membranous margin (in Mal. spp.) producing mucilage (?always), with or without a short ligule; limb glabrous or with numerous, small hard papillae, sometimes with a stout nerve in either margin. Flowers ♀♂, in terminal, few- to many-flowered heads, 3-merous, yellow to white, ephemeral, each in the axil of a conspicuous bract; bracts conchate, imbricate, spirally arranged, lower ones sterile; one to few flowers simultaneously in anthesis. Peduncles scape-like, terete to compressed, sometimes winged or ribbed, glabrous or with numerous hard papillae, at the base with some sheaths provided with a short limb. Bracts entire, ciliate, fimbriate or lacerate, with one complete main nerve and some complete or incomplete longitudinal secondary (descending) nerves, in the apical part mostly with a small minutely-papillose field. Calyx zygomorphic; lateral sepals navicular, with entire, dentate or ciliate crest, wings membranous, entire, glabrous or ciliate; median sepal membranous, spathelliform or cap-shaped, enveloping the corolla, mostly obovate, 1-3(-5)-nerved, pushed out by the corolla in anthesis(?always). Corolla actinomorphic, ephemeral; petals with an orbicular to obovate limb and a long, narrow claw, free, cohering mutually or by the staminodes. Stamens mostly 3 fertile epipetalous inserted on the petals and 3 alternating staminodes, staminodes rarely absent, or all stamens fertile; filaments short; anthers basifix, dehiscing lengthwise extrorsely. Ovary superior, sessile to stipitate (in Australian spp. sometimes with 3 hard swellings at the top), 1- or 3-celled, or incompletely 3-celled. Placentas parietal, central, or basal, with ~ ovules; styles filiform, apex 3-fid, stigmas mostly capitate. Fruit shape similar to that of the ovary but larger, loculicidally 3-valved. Seeds ellipsoid to obovoid, often ribbed, with a long funicle.|
Distr. Xyridaceae are confined to the tropics throughout the world including the southern parts of North America; east of Malaysia and Australia hitherto only recorded from the Patau group (Korror) and New Caledonia.