398 MONOCOTYLEDONOUS PLANTS. 



15. ORTHOPOGON. Brmim. 



Spike compound. Glume 2-valved, nearly equal, 2-flow- 

 ered ; valves unequally awned. Florets dissimilar ; outer 

 one staminiferous or neuter,'!- or 2-valved ; inner pistiliferous 

 surrounding the seed. Triandria. Digynia. 



0. echinatus Spreng. : spikes alternate,, secund, simple ; rachis 

 triquetrous, smoothish ; glumes nerved, muricate-hispid ; leaves and 

 sheaths smooth, striate. Panicum echinatunt WiUd. 



HAB. Penn. If. -Mr. Schweinitz informs me that a variety of 

 this species occurs at Bethlehem, Penn. 



16. DIGITARIA. HaUtr. 



Inflorescence digitate or fascicled. Spikelets in pairs, on 

 short bifid peduncles. Glume 2-valved, the lower very mi- 

 nute. Lower floret abortive, the paleae membranous. . "Upper 

 floret perfect, the paleae subcoriaceous, hardened. Seed 

 slightly furrowed. Triandria. Digynia. 



1. D. sanguinalis Scop. : spikes digitate, erect, somewhat spreading ; 

 leaves and sheaths pilose ; florets oblong, pubescent at the edge. 

 Panicum sanguinale Linn. Big. 



HAB. Cultivated grounds. Can. to Car. Aug., Sept. . 

 Culm 1 2 feet long, decumbent or assurgent. Spikes 4 6. 



Grab Grass. 



2. D. glubra R. $ S. .- spikes digitate, subalternate, (34) spread- 

 ing ; leaves and sheaths smooth ; spikelets ovate, crowded ; glume 

 equal to the abortive floret, both hairy. D. isckacmum Muhl. D. pas- 

 palotties Mich. 



HAB. Sandy fields. N. Y. to Vir. Aug., Sept. . Culm a 

 foot long, mostly decumbent. Spikes mostly 3, about 2 inches 

 long. 



\ D. serotina Mich. : decumbent ; leaves and sheaths very pubes- 

 cent ; spikes numerous, setaceous ; spikelets all pedicellate ; lower 

 glume very minute. D. riUosa EIL 



HAB. Wet places. N. Y. Muhl. S. to Car. June -Aug. . 

 Culm 1218 inches long. Spikes 23 inches long. 



4. D. JMformis Ell. : culm erect, filiform ; leaves somewhat smooth ; 

 spikes 2 4, filiform, erect ; spikelets in threes, all pedicellate ; glumea 

 1-valved, as long as the abortive floret. D. pilosa Mich. ? 



HAB. Sandy fields. N. J. to Geor. Aug. Q.Culm 12 feet 

 high. Spikes mostly 2, alternate, long. 



17. PASPALUM. Linn. 



Glwne 2-valved, 1-flowered, membranaceous, equal, closely 

 pressed to the two plano-convex palecc. Seed coated with the 

 paleae. Flowers in unilateral spikes. Triandria. Digynia. 



