Acoraceae

Abstract

Acoraceae Martinov, Tekhno-Bot. Slovar (1820) 6. Perennial, glabrous, aromatic herbs, growing in marshes or as emergent aquatics; laticifers and raphides absent; aerenchyma present. Rhizome creeping, much branched, lacunose, with specialized aromatic oil cells; rooting on the lower side and bearing leaves at apex. Leaves distichous, bases overlapping, unifacial, ensiform, not differentiated into petiole and blade; intravaginal squamules present in leaf axils; venation parallel. Inflorescence solitary, terminal, borne laterally on leaf-like scape (usually interpreted as peduncle and spathe; peduncle with two separate vascular systems), peduncle triangular; continuation shoot arising in axil of leaf preceding inflorescence; the so-called spathe much longer than spadix, erect, persistent (appearing merely as a vertical leaf-like extension); spadix jutting out at an angle from peduncle, sessile, conoid, cylindrical and finger-like or slender and tail-like; flowering from the base to the top. Flowers bisexual, perigoniate, densely arranged, bractless, trimerous; tepals 6 in two whorls of 3, free, thin, fornicate; stamens 6 in two whorls of 3, free, filaments linear-oblong and flattened, anthers introrse, thecae rounded-ellipsoid, subopposite, dehiscing by longitudinal slit, connective inconspicuous; pollen monosulcate, ellipsoid, small (15-20 μm), exine shallowly and remotely or more densely foveolate, otherwise psilate, apertural exine subpsilate; gynoecium (pistil) obconic-cylindric, only slightly exceeding tepals, ovary 2-or 3-locular, ovules several per locule, orthotropous, pen-dent on apical placenta, both integuments bearing trichomes, inner integument longer than outer forming the micropyle; stigma minute (more or less punctate), subsessile (there is a broad stylar region visible in LS); fruit a few-seeded berry, oblong-obovoid with thin, leathery pericarp, enclosed by the tepals, more or less whitish with brownish stigma remnant when fresh, soon becoming straw-brown (A. calamus) or yellowish to yellow-white (A. gramineus) at maturity, 1-5(-9)-seeded; seed oblong to ellipsoid or ovoid, testa light brown, with small pits (slightly foveolate in A. calamus) or smooth (A. gramineus), long integumentary trichomes (bristles) present at the micropyle (A. gramineus) or absent (A. calamus); embryo axile, cylindric (A. calamus) or conoid (A. gramineus), with perisperm and abundant endosperm. Chromosomes: 2n = (22) 24, 36, (44), 48.