Isachne

The description in Roemer and Schultes (1817) was taken from the manuscript of Roth (Nov. Pl. Sp. 58. 1821).

This taxon grades into small, slender forms of Isachne globosa and is sometimes included within that species (as the synonym I. dispar). However, this creates an unacceptably wide range of variation within I. globosa. Typical forms of I. pulchella are quite different from typical forms of I. globosa. Isachne pulchella, as recognized here, comprises small, delicate plants with short, broad leaf blades, hairy nodes with a glandular ring below, small spikelets with clearly dissimilar florets, a soft, herbaceous lower floret lacking a dorsal groove, and a pubescent upper floret. The anthers are shorter than in small forms of I. globosa.

Annual. Culms very slender, straggling, branching and rooting at lower nodes, 10–25 cm tall, nodes hispid with a glandular ring below. Leaf sheaths shorter than internodes, papillose-hispid at base above node, otherwise pilose or subglabrous, outer margin ciliate; leaf blades ovate or ovate-lanceolate, 2–3 × 0.8–1 cm, scabrid to thinly hispid, base cordate-amplexicaul with pectinate margin, apex shortly acuminate; ligule ca. 2 mm. Panicle narrowly ovate to pyramidal in outline, 2.5–5 cm, glandular; primary branches inserted singly, stiffly and regularly spreading with branchlets to their base; pedicels mostly shorter than spikelets. Spikelets plumply elliptic, 1.3–1.8(–2) mm, gray-green or purplish green; florets clearly dissimilar; lower floret male, upper floret bisexual or female; glumes slightly shorter than lower floret; lower glume elliptic-oblong, 5-veined, upper glume broadly elliptic, 7-veined both glabrous, apex obtuse; lower lemma herbaceous, elliptic-oblong, dorsally flattened, smooth, glabrous; anthers 0.3–0.5 mm; upper lemma slightly shorter, crustaceous, strongly plano-convex, pubescent. Fl. and fr. May–Oct.

Marshy ground and shallow water, gregarious and forming patches. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hunan, Jiangxi, Taiwan, Yunnan, Zhejiang [Bangladesh, India, Malaysia, Nepal, Thailand, Vietnam].

Isachne dispar Trinius; I. heterantha Hayata; Panicum bellum Steudel, nom. illeg. superfl.; Sphaerocaryum pulchellum (Roth) Merrill; Steudelella pulchella (Roth) Honda.

Annuals, Terrestrial, not aquatic, Stems trailing, spreading or prostrate, Stems nodes swollen or brittle, Stems terete, round in cross section, or polygonal, Stems branching above base or distally at nodes, Stem nodes bearded or hairy, Stem internodes hollow, Stems with inflorescence less than 1 m tall, Stems, culms, or scapes exceeding basal leaves, Leaves mostly cauline, Leaves conspicuously 2-ranked, distichous, Leaves sheathing at base, Leaf sheath mostly open, or loose, Leaf sheath smooth, glabrous, Leaf sheath and blade differentiated, Leaf blades disarticulating from sheath, deciduous at ligule, Leaf blades lanceolate, Leaf blade auriculate, Leaf blades 2-10 mm wide, Leaf blades 1-2 cm wide, Leaf blades mostly flat, Leaf blades more or less hairy, Leaf blades glaucous, blue-green, or grey, or with white glands, Ligule present, Ligule a fringed, ciliate, or lobed membrane, Ligule a fringe of hairs, Inflorescence terminal, Inflorescence an open panicle, openly paniculate, branches spreading, Inflorescence solitary, with 1 spike, fascicle, glomerule, head, or cluster per stem or culm, Inflorescence branches more than 10 to numerous, Flowers bisexual, Flowers unisexual, Spikelets pedicellate, Spikelets sessile or subsessile, Spikelets dorsally compressed or terete, Spikelet less than 3 mm wide, Spikelets with 2 florets, Spikelets solitary at rachis nodes, Spikelets bisexual, Spikelets disarticulating above the glumes, glumes persistent, Rachilla or pedicel glabrous, Glumes present, empty bracts, Glumes 2 clearly present, Glumes equal or subequal, Glumes equal to or longer than adjacent lemma, Glum es 3 nerved, Glumes 4-7 nerved, Glumes 8-15 nerved, Lemmas thin, chartaceous, hyaline, cartilaginous, or membranous, Lemma similar in texture to glumes, Lemma 5-7 nerved, Lemma glabrous, Lemma body or surface hairy, Lemma apex truncate, rounded, or obtuse, Lemma awnless, Lemma margins thin, lying flat, Lemma straight, Palea present, well developed, Palea membranous, hyaline, Palea longer than lemma, Stamens 3, Styles 2-fid, deeply 2-branched, Stigmas 2, Fruit - caryopsis.