POACEAE 69 



18. LIMNODEA L. H. Dewey. 



Somewhat branched tufted grasses, with the stems usually decumbent at the base, nar- 

 row flat leaf -blades, and narrow slender elongated contracted panicles. Spikelets 1 -flow- 

 ered, narrow, scattered on the panicle branches. Scales 3, the 2 outer empty, about equal 

 in length, hispidulous or pilose, the nerves inconspicuous, the third scale scarcely shorter, 

 thin, the apex shortly 2-toothed or 2-cleft, with an elongated slender geniculate or flexuous 

 awn, which is a little twisted at the base, arising from between the teeth, the scale enclos- 

 ing a somewhat shorter 2-keeled narrow hyaline palet and a perfect flower. Stamens 3. 

 Styles short, distinct. Stigmas shortly pilose. [Thurberia Benth., not A. Gray.] 



1. Limnodea Arkansana (Nutt. ) L. H. Dewey. Stems tufted, 2-4 dm. tall : leaf- 

 sheaths glabrous or more or less hirsute ; blades erect, 3-12 cm. long, 2-8 mm. wide, more 

 or less pubescent on both surfaces : panicle narrow, often partially included at the base, 

 7-17 cm. long : spikelets 3.5-4 mm. long, the 2 outer scales tuberculate-hispidulous, the 

 awn of the third scale geniculate, spiral at the base, 8-10 mm. long. [ Thurberia Arkansana 

 (Nutt.) Benth.] 



In dry soil, Florida, Arkansas and Texas. Spring. A form known as L. Arkansana pildsa (Trin.) 

 Nash (Sclerachne pilosa Trin.) is like the preceding, but the two outer scales are densely hirsute. It 

 occurs in Louisiana and Texas. 



19. RBIMARIA Fluegge. 



Perennial grasses, usually diffusely branching, with ascending stems, and the inflores- 

 cence composed of 2 or more secund racemes. Spikelets 1-flowered, awnless, acuminate, 

 subsessile, alternately disposed in 2 rows on a narrow or somewhat dilated rachis. Scales 

 2, the first empty, membranous, 3-5-nerved, acute, the second scarcely shorter and enclos- 

 ing the slightly shorter palet and a perfect flower. Stamens 2. Styles distinct to the base. 

 Stigmas long-plumose. 



1. Reimaria oligostachya Munro. Smooth and glabrous. Stems compressed, 4-8 

 dm. long : leaf -sheaths compressed ; blades erect or ascending, 5-15 cm. long, 2-4 mm. 

 wide : racemes one-sided, in pairs at the summit of the stem, or sometimes with an addi- 

 tional one a short distance below, 5-7 cm. long : spikelets broadly lanceolate, about 5 mm. 

 long, about twice as long as the rachis-internodes, the first scale 9-nerved, the four nerves 

 on each side close together and rather distant from the midnerve. 



Along shores and in ditches, Florida. Summer. 



20. F ASP ALUM L. 



Usually perennial grasses with flat leaf -blades and an inflorescence composed of one or 

 more unilateral racemes, arranged singly, in pairs, or in panicles. Spikelets 1-flowered, 

 obtuse, or rarely short-acuminate, nearly sessile or short-pedicelled, alternately disposed, 

 singly or in pairs, in 2 rows on one side of a narrow and usually winged rachis. Scales 3, 

 rarely 4, the 2 outer, rarely 3, empty, membranous, usually equal in length, the flowering 

 scales glabrous and shining, more or less convex, with its back turned toward the rachis, 

 at length indurated, enfolding a shorter palet of similar texture and a perfect flower. Sta- 

 mens 3. Styles distinct to the base, often elongated. Stigmas plumose. 



A. Rachis dilated, its broad margins membranous and at maturity inrolled 



on the spikelets. 

 Rachis long-acuminate, extending beyond the spikelets which are 1.5 



mm. long or less. 1. P. mucronatum. 



Rachis acute, not extended ; spikelets about 2 mm. long or more. 2. P. mcmbranaceum. 



B. Rachis more or less winged, rarely wingless, its margins not membranous 



nor enclosing the spikelets. 



a. Stems with 1-several raceme-bearing naked branches from the upper- 

 most sheath. 



1. Leaf-blades glabrous on the lower surface, or the midnerve some- 

 times pubescent. 

 *Blades conspicuously ciliate. 



Uppermost sheath with the margins glabrous. 



Spikelets glabrous, or nearly so, rounded at the apex. 3. P. blepharophyUum. 



Spikelets densely pubescent, obtusely apiculate at the apex. 4. P. propinquum. 

 Uppermost sheath with the overlapping margin prominently cili- 

 ate. 



Spikelets orbicular, hence as broad as long, straw-color. 5. P. stramincum. 



Spikelets broadly obovate to oval, longer than broad, green. 

 Spikelets densely pubescent, 2 mm. long, the leaves scat- 

 tered along the stem. 6. P. Chapmanii. 



