Wrinkled Joint Tail Grass

Coelorachis rugosa (Nutt.) Nash
Rottboellia rugosa Nutt. Gen. 1 : 84. 1818.
Rottboellia corrugata Baldw. Am. Jour. Sci. 1 : 355. 1819.
Rottboellia rugosa Chapmani Hack, in DC. Monog. Phan. 6 : 308. 1889.
Manisuris rugosa Kuntze, Rev. Gen. 780. 1891.
Manisuris Chapmani Nash, in Small, Fl. SF. U. S. 56. 1903.
Stems tufted, much compressed, 6-15 dm. tall, stout; leaf-sheaths much flattened, broad, keeled ; blades 4 dm. long or less, 10 mm. wide or less; racemes exserted or somewhat included at the base, sometimes spreading, 4-8 cm. long, straight or a little curved, the rachis-internodes often much contracted at the base, glabrous or puberulent ; sessile spikelet 3.5-5 mm. long, about equaling or a little exceeding the internode, the first scale often 2-toothed at the obtuse apex, strongly transversely wrinkled, the wrinkles much elevated and often extending across the entire width of the scale, the longitudinal ridges usually rather prominent ; pedicellate spikelet smaller, of 2 scales, empty, or sometimes bearirfg a staminate flower.
Type locality : Florida.
Distribution : Southern New Jersey, Delaware, and Maryland to Florida and Texas.

Perennials, Terrestrial, not aquatic, Stems nodes swollen or brittle, Stems erect or ascending, Stems caespitose, tufted, or clustered, Stems compressed, flattened, or sulcate, Stem nodes bearded or hairy, Stem internodes solid or spongy, Stems with inflorescence less than 1 m tall, Stems with inflorescence 1-2 m tall, Stems with inflorescence 2-6 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 or blade keeled, Leaf sheath and blade differentiated, Leaf blades linear, Leaf blades 2-10 mm wide, Leaf blades mostly flat, Leaf blade margins folded, involute, or conduplicate, Leaf blades mostly glabrous, Ligule present, Ligule a fringed, ciliate, or lobed membrane, Ligule a fringe of hairs, Inflorescence terminal, Inflorescence a dense slender spike-like panicle or raceme, branches contracted, Inflorescence solitary, with 1 spike, fascicle, glomerule, head, or cluster per stem or culm, Inflorescence single raceme, fascicle or spike, Flowers bisexual, Flowers unisexual, Spikelets sessile or subsessile, Spikelets dorsally compressed or terete, Spikelet less than 3 mm wide, Spikelets with 2 florets, Spikelets paired at rachis nodes, Spikelets in paired units, 1 sessile, 1 pedicellate, Pedicellate spikelet rudimentary or absent, usually sterile, Spikelets bisexual, Spikelets disarticulating below the glumes, Spikelets closely appressed or embedded in concave portions of axis, Rachilla or pedicel glabrous, Glumes present, empty bracts, Glumes 2 clearly present, Glumes equal or subequal, Glumes equal to or longer than adjacent lemma, Glumes keeled or winged, Glume rugose with transverse wrinkles, Glumes 1 nerved, Lemmas thin, chartaceous, hyaline, cartilaginous, or membranous, Lemma 5-7 nerved, Lemma glabrous, Lemma apex acute or acuminate, Lemma awnless, Lemma margins thin, lying flat, Lemma straight, Palea present, well developed, Palea membranous, hyaline, Palea longer than lemma, Palea 2 nerved or 2 keeled, Stamens 3, Styles 2-fid, deeply 2-branched, Stigmas 2, Fruit - caryopsis.

Coelorachis rugosa là một loài thực vật có hoa trong họ Hòa thảo. Loài này được (Nutt.) Nash mô tả khoa học đầu tiên năm 1909.