POACEAE 139 



Sheaths smooth or nearly so : flowering scales 1.75 mm. long, broad, obtuse, 



the nerves densely pilose excepting at the summit. 5. L. Nealleyi. 



Sheaths very rough : flowering scales 2.5 mm. long, narrow, acute, the nerves 



pilose below the middle. 6. L. scdbra. 



1. Leptochloa mucronata (Michx. ) Kunth. Stems 3-12 dm. tall, finally branching : 

 leaf-sheaths, at' least the lower ones, generally more or less hirsute ; blades 6-25 cm. long, 

 1 cm. wide or less, rough : inflorescence 1.5-5 dm. long, usually included at the base : 

 spikes slender, commonly elongated, ascending, 5-15 cm. long : spikelets 2.5-3 mm. long : 

 scales usually 5 ; the 2 outer empty, acute, equal, or the first somewhat shorter than the sec- 

 ond , the first commonly a little shorter than the first flowering scale, rarely somewhat ex- 

 ceeding it ; flowering scales about 1.5 mm. long, rounded at the emarginate apex, the nerves 

 pilose, excepting at the apex, the hairs copious and long. 



In fields, Virginia to Florida and California. Summer. 



2. Leptochloa attenuata Nutt. Stems tufted, 2-6 dm. tall, finally branching : leaf- 

 sheaths more or less hirsute ; blades 4-20 cm. long, 3-8 mm. wide, rough, sparingly hir- 

 sute above: inflorescence 1.5-2 dm. long, usually included at the base : spikes slender, 

 spreading or ascending, 4-10 cm. long : spikelets 1.6-2 mm. long : scales 5 or 6 ; the 2 outer 

 empty, subulate, acuminate, awn-pointed, generally about equal, or the first shorter than 

 the second which reaches the apex of the second flowering scale ; flowering scales a little 

 less than 1 mm. long, rounded at the apex, the nerve-hairs scant and very short. 



In low sandy bottoms, Illinois to the Indian Territory. Fall. 



3. Leptochloa virgata (L. ) Beauv. Stems 2-10 dm. tall: leaf -sheaths glabrous; 

 blades 5-30 cm. long, 5-15 mm. wide, often rough above : inflorescence 1-2.5 dm. long, 

 exserted : spikes numerous, erect or ascending, usually in whorls, sometimes scattered or 

 in pairs, 3-12 cm. long, rather stout : spikelets 3.5-4 mm. long : scales 6-9 ; the 2 outer 

 empty, broad, acute ; flowering scales 2-2.5 mm. long, the midnerve glabrous, sometimes 

 excurrent in a short point or awn, the lateral nerves pubescent for the upper two-thirds. 



In sandy soil, Texas. Also in Mexico, South America and the West Indies. Summer. 



4. Leptochloa Doming6nsis ( Jacq. ) Trin. Stems 2-10 dm. tall, finally branching : 

 leaf-sheaths glabrous or sparingly hirsute ; blades 1-3 dm. long, 1 cm. wide or less, some- 

 times rough beneath, hirsute above : inflorescence 1-2 dm. long, its axis smooth : spikes 

 erect or somewhat ascending, usually numerous, the lower ones 3-10 cm. long : spikelets, 

 exclusive of the awns, 2-3 mm. long : scales 4 or 5 ; the 2 outer empty unequal, acute, 

 shorter than the spikelet ; flowering scales 1.75-2. 25 mm. long, acute, internerves glabrous or 

 appressed -pubescent, the lateral nerves pilose for part way above the middle, the midnerve 

 hispidulous above the middle and extending into an awn \ to fully as long as the body. 



In sand, peninsular Florida and southern Texas. Also in tropical America. Summer. 



5. Leptochloa Nealleyi Vasey. Stems 4-10 dm. tall : leaf-sheaths smooth and gla- 

 brous ; blades 4-20 cm. long, 2-4 mm. Avide, roughish ; inflorescence 1.5-3.5 dm. long, in- 

 cluded at the base : spikes very numerous, short and stout, 2-5 cm. long, appressed : spike- 

 lets crowded, about 3 mm. long : scales 5 or 6 ; the 2 outer empty, broad, obtuse, the first 

 about 2 as long as the second which is % as long as the spikelet or less ; flowering scales 1.75 

 mm. long, rounded at the apex, the midnerve sometimes excurrent, the nerves pilose, ex- 

 cepting at the apex, with long hairs. 



In low land, central and southern Texas. Summer. 



6. Leptochloa scabra Nees. Rough throughout. Stems 1 m. tall or less : leaf- 

 sheaths glabrous ; blades 2-4 dm. long, 1 cm. wide or less : inflorescence 2-4 dm. long, in- 

 cluded at the base : spikes very numerous, erect-ascending, sometimes curved, the lower 

 ones 5-8 cm. long : spikelets 3.5-4 mm. long : scales usually 6 ; the 2 outer empty, acute, 

 the first 2 as long as the second which is less than 5 as long as the spikelet ; flowering scales 

 about 2.5 mm. long, acute, the nerves pilose below the middle, the midnerve also hispidu- 

 lous above the middle and usually excurrent in a short awn. 



In ditches and fields, Louisiana. Probably introduced. Fall. 



90. ACAMPTOCLADOS Nash. 



Perennial tufted grasses, with stiff" stems, flat or involute leaf-blades and a panicle 

 composed of scattered and distant widely spreading rigid branches. Spikelets scattered 

 and distinct, singly disposed in two rows, sessile, 4-6-flowered. Scales 6-8, firm : the 2 

 lower empty, acuminate, about equal, the first 1-nerved, the second usually 3-nerved ; 

 flowering scales very acute, becoming harder in fruit, 3-nerved, the nerves glabrous, the 

 lateral nerves vanishing at the margin below the apex ; palet compressed, its 2 nerves cilio- 

 late, gibbous at the base. Stamens 3. Styles distinct. Stigmas plumose. 



