Japanese Panic Grass

Annuals; culm weak, slender, 30-120 cm high, branching and prostrate. Blade 5-30 cm long, 4-10 mm wide, thin; sheath glabrous, margins ciliate; ligule truncate, membranaceous, ca. 0.5 mm long, irregularly fringed with hairs. Panicle open, ovate or deltoid, 12-40 cm in length and width. Spikelets acute, ca. 2 mm long, elliptic, faintly dark green, sometimes purplish; lower glume triangular, acuminate or acute, 1/3 as long as spikelet; upper glume and lower lemma similar, acute, finely 5-veined, membranaceous, elliptic, 15-18 mm long, obtuse, smooth, shiny, greyish brown when mature.

Annual. Culms erect or ascending, sometimes rooting at lower nodes, 30–180 cm tall, nodes glabrous. Leaves cauline; leaf sheaths striate, glabrous, ciliate on the margins, especially toward the throat; leaf blades linear, 5–20 × 0.5–1.5 cm, subglabrous, base rounded, apex acuminate; ligule ca. 0.5 mm, a ciliolate membrane. Panicle ovate or orbicular in outline, 10–40 cm, loose, much branched; branches slender, flexuous, scabrid, with the spikelets in pairs and clustered toward the ends of the branches. Spikelets elliptic, 2–2.5 mm, sparsely puberulous; lower glume ovate, 1/2 length of spikelet, 1–3-veined, acute or acuminate; upper as long as spikelet, 5-veined; lower lemma similar to upper glume, palea absent; upper floret as long as spikelet, pale yellow, smooth, shiny. Fl. and fr. Sep–Nov. 2n = 36.

India, Malesia, Australia, China and Japan. Taiwan, in lowland forest margin.

Moist places. Anhui, Fujian, Guangdong, Guizhou, Hainan, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Shandong, Sichuan, Taiwan, Yunnan, Zhejiang [India, Japan, Korea, Philippines; Australia, Pacific Islands].

Panicum acroanthum Steudel; P. acroanthum var. brevi-pedicellatum Hackel.

Annuals, Terrestrial, not aquatic, Stems nodes swollen or brittle, Stems geniculate, decumbent, or lax, sometimes rooting at nodes, Stems caespitose, tufted, or clustered, Stems terete, round in cross section, or polygonal, Stems compressed, flattened, or sulcate, Stems branching above base or distally at nodes, 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 hairy, hispid or prickly, Leaf sheath and blade differentiated, Leaf blades linear, Leaf blades 2-10 mm wide, Leaf blades 1-2 cm wide, Leaf blades mostly flat, Leaf blade with prominently raised or widened midvein, Leaf blades mostly glabrous, Leaf blades scabrous, roughened, or wrinkled, Ligule present, Ligule a fringed, ciliate, or lobed membrane, Inflorescence terminal, Infloresce nce an open panicle, openly paniculate, branches spreading, Inflorescence solitary, with 1 spike, fascicle, glomerule, head, or cluster per stem or culm, Inflorescence lax, widely spreading, branches drooping, pendulous, Inflorescence branches more than 10 to numerous, Flowers bisexual, Spikelets pedicellate, Spikelets dorsally compressed or terete, Spikelet less than 3 mm wide, Spikelets with 1 fertile floret, Spikelets with 2 florets, Spikelet with 1 fertile floret and 1-2 sterile florets, Spikelets solitary at rachis nodes, Spikelets all alike and fertille, Spikelets bisexual, Spikelets disarticulating below the glumes, Rachilla or pedicel glabrous, Glumes present, empty bracts, Glumes 2 clearly present, Glumes distinctly unequal, Glumes equal to or longer than adjacent lemma, Glume equal to or longer than spikelet, Glumes 3 nerved, Glumes 4-7 nerved, Lemma similar in texture to glumes, Lemma 3 nerved, Lemma 5-7 nerved, Lemma glabrous, Lemma apex truncate, rounded, or obtuse, Lemma apex acute or acuminate, Lemma awnless, Lemma margins inrolled, tightly covering palea and caryopsis, Lemma straight, Palea present, well developed, Palea about equal to lemma, Stamens 3, Styles 2-fid, deeply 2-branched, Stigmas 2, Fruit - caryopsis, Caryopsis ellipsoid, longitudinally grooved, hilum long-linear.