Mostly tall perennials, with narrow flat leaves and cylindric jointed spikes, terminal and from the upper axils. Spikelets in pairs at each node of the excavated rachis, one sessile and perfect, the other with a pedicel and either staminate or empty. Scales of the perfect spikelet 4, the outermost thick and coriaceous, covering, together with the pedicel of the sterile spikelet, the excavation in the rachis; second scale chartaceous; third and fourth hyaline, the latter subtending the palet and perfect flower. Stamens 3. Styles distinct. Grain free. [Name Greek, meaning hollowed rachis.]

About 20 species, widely distributed in tropical and temperate countries.

Leaf-sheaths broad, compressed, keeled; plants without rootstocks.




Leaf-sheaths narrow, round, not keeled; plants with creeping rootstocks.




2 Coelorachis Brongn In Duperr Voy Coq Bot Phan 64 255

I. Coelorachis Rugosa (Nutt.) Nash. Wrinkled Joint-Grass

Fig. 255

Rottboellia rugosa Nutt. Gen. 1: 84. 1818. R. corrugata Baldw. Am. Journ. Sci. 1: 355. 1819. Manisuris rugosa Kuntze, Rev. Gen. 780. 1891. Manisuris rugosa Chapmani Scribn. Mem. Torr.

Club 5: 28. 1894. C. rugosa Nash, N. A. Fl. 17: 86. 1909.

Smooth and glabrous. Culms 2°-5° tall, compressed, much-branched above, branches spreading; sheaths compressed; blades flat, acuminate, 6'-1 1/2° long, 1"-5" wide; racemes partially included in the sheath or more or less exserted, 1 1/2'-2 1/2' long; outermost scale of the sessile spikelet oblong-ovate to ovate, 1 3/4"-2 1/2" long, strongly transversely rugose, the wrinkles continuous or interrupted.

In wet soil along the coast, southern New Jersey to Maryland, Florida and Texas. June-Sept.

2. Coelorachis Cylindrica (Michx.) Nash. Pitted Joint-Grass

Fig. 256

Tripsacum cylindricum Michx. Fl. Bor. Am. 1: 60.

1803. Rottboellia cylindrica Torr. Pac. R. R. Rep. 4: 159.

1857. Manisuris cylindrica Kuntze, Rev. Gen. 779. 1891. Coelorachis cylindrica Nash, N.A.F1. 17: 85. 1909.

Culms from creeping rootstocks, round, I°-3 1/2° tall, slender; blades 1° long or less, 1/2"-1 1/2" wide; racemes 4'-8' long, the rachis barely if at all contracted at the nodes; sessile spikelets 2 1/4"-2 1/2" long, about equalling the internodes, the first scale more or less pitted in longitudinal lines, or rarely unpitted, the pits often containing a subulate hair; pedicellate spikelets reduced to 1 or 2 short scales, the pedicel linear, shorter than the sessile spikelet and curved around its margin.

In sandy soil at low elevations, Georgia and Florida to Missouri, Oklahoma and Texas. Summer.

2 Coelorachis Cylindrica Michx Nash Pitted Joint G 256