ORDER 155. GRAMINE^E. 



38 ( J 



c A\vns about equal, spreading. Lower gl. longer than the upper Nos. 57 



Glumes equal, or the lower shorter Nos. 8, 9 



1 A. tnberculosa N. Culm rigid, 820'. with tubercles in the axils of the numerous 

 branches; pan. large and loose; glume linear, awned, 1'; triple awn (d) 2', united 

 half-way up, thence involved and spreading. (T) Mountains, N. J., and W. 

 8 A. cllcUotoma MX. (a) Culm 812', dichotomously branched ; gl. 34" ; lateral 

 awns erect, minute, the middle awn (6) as long as the pale (3"), twice bent to the 

 form of a bayonet. (D Dry ^andy fields : common. 



3 A. ramosissima Engelm. Culms diffusely branched; gl. 9 10", awn-pointed ; 



lateral awns 2 1 , middle awn 1'. spreading. (I) Sands, 111., Ky. 



4 A. gracilis E:i. Very slender. | IK; pan. virgate, 4 8'; glume and flower equal* 



(2J3"); middle awn 910", horizontal, the lateral erect. Sandy places. 

 0. cir^ata. Taller (2 3f), ran. If; gl. and fl. shorter (2"). S. (Chapman}. 



5 A. lanata Poir. Culms 2 4f, stout, branched from base; Ivs. flat, with woolly 



sheaths; pan. 1 2f, woolly in its axils; upper glume, lower (purplish) pale and lat- 

 eral awns each 4 5", middle awn some longer. ii Sandy soils, S. 



6 A. spicifirmis Ell. Culms 1 3f, rigid, simple; Ivs. rolled, rigid, smooth; pan. 



spike-form, dense ; flower 1' long, awns as long, gl. much shorter. V. Wet sands, S. 



7 A. purpurascens Poir. (c) Culms slender, 2 3f; Ivs. scarcely rolled ; pan. If 



long, loosely spicate; glum-; and fl. 45", purplish ; awns 1', spreading. ii Sandy. 



8 A. stricta MX. Culms 2 3f, strictly erect, with long rigid rolled Ivs.; pau. loosely 



racemous, If; gl. 67", fl. 6", lateral awns 79", central 915". if. Va., and S. 



9 A. oligantha MX. Culms 1 IK, in tufts; raceme few-flowered; glume and fl. 9", 



very slender, awns capillary, divaricate, 1830" long. Prairies, W. and S. 



17. PASPALUM, L. Spikelets plano-con- 

 vex, in one-sided spikes. Glumes (apparently) 

 2, membranous, equal, ovate or orbicular, closely 

 applied to the fertile flower. Grain coated with 

 the smooth coriaceous pales. (But theoretically, 

 the lower glume is obsolete, and its place sup- 

 plied by the empty pale of an abortive flower. 

 In Nos. 15 17 the lower glume appears, under a 

 lens, as a mere rudiment.) Spikes linear, the 

 flowers in 2 4 rows. 



PASPALUM. Spikelets round or round-oval, obtuse. 



Spikes alternate... (*) 

 DIGITAUIA. Spikelets ovate to lanceolate, acute. 



Spikes often digitate.. .(**) 



* Terminal spike mostly solitary, rarely 2, V wide, long-stalked No. 1 



* Terminal spikes mostly 3 or 4, 2" wide. Spikelets in 2 rows Nos. 2,' 3 



* Terminal spikes mostly 4 or 5. Spikelets close, in 3 or 4 rows Nos. 4 (i 



Spikelets in remote pairs No. 7 



** Rachis le*U-like, broader than the spikelets. Spikes alternate .. 

 ** Kachis narrower than the spikelets. Spikes digitate. . .(a) 



a Glumes (gl. and pale) about equal, as long as the flower. . .(ft) 



a His. (both conspicuous) one or both, very short. Spks. 4 9. Nos. 16, 17 



b Spike* spreading, always two in Nos. 10, 11 ; two -six in No. 12 



L- Spikes erect. Ttachis fiat, spikelets by 1's or2's, close Nos. 13, 14 



Rachis filiform, spikelets by 3'?, loose No. 13 



1 P. setaccum MX. Culm Blender, ascending, 1 ?f. naked above ; Ivs. linear, fiat, 

 23" \\-idc, soft, hairy ; spike? very slender, 21', 1 or 2 on the long peduncle, often 



