14 



POACEAE. 



14, OPLISMENUS Beauv. Creeping plants with broad flat leaf -blades 

 and an inflorescence composed of spikes, bearing on the lower side scattered 

 clusters of a few spikelets. Scales 4, the 3 outer membranous, the first and 

 second awned, the third usually awned, the fourth one shorter than the others, 

 obtuse, awnless, chartaceous, finally indurated. 



1. O. hirtellus (L.) E. & S. Stems prostrate, rooting at the nodes: leaf-blades 

 ovate to ovate-lanceolate, acuminate, 1.5-6 cm. long: panicle 2-8 cm. long, its 

 short branches erect to spreading: spikelets 2.5-3 mm. long, the longer awns 

 6-8 mm. long. — Hammocks. — F. K, (Ber., Bah., Cuba, Ant.) 



15, PANICUM L, Erect, or diffuse herbaceous plants varying much in 

 habit, with elongate or broad leaf-blades, and the spikelets in open or con- 

 tracted panicles. Spikelets 1-2-flowered, lanceolate, oblong, ovate to obovate 

 or globose, obtuse to acute or acuminate. Scales 4, the 3 outer membranous, 

 the first and second empty, the first usually much shorter than the spikelet, 

 sometimes minute, the third one empty or enclosing a shorter hyaline palet and 

 often also a staminate flower, the fourth scale shorter and usually more obtuse 

 than the others, chartaceous, glabrous and shining, at length indurated, enclos- 

 ing a palet of similar texture and a perfect flower. — Panic-grass. 



Spikelets disposed singly or In pairs in one-sided racemes, the pedicels short. 



I. Paspaloidea. 

 Spikelets in panicles, but not borne in one-sided racemes : the 

 pedicels short or long. 

 Basal leaf-blades long and narrow, similar to those of the 

 stem : no rosulate tufts of leaves in the fall : spike- 

 lets lanceolate to ovate, usually the former, acute 

 or acuminate, rarely obtuse. 

 Basal leaf-sheaths round or but little flattened, not 

 keeled. 

 Annuals, or perennials without rootstocks or stolons. 

 Perennials with long stolons or rootstocks. 



Kootstocks and stolons naked or with few large 



scales : sand-binders. 

 Rootstocks, at least when young, and stolons 

 covered with numerous small broad acute 

 scales. 

 Basal leaf-sheaths much compressed, broad, keeled, 

 often equitant. 

 Basal leaf-blades commonly imlike those of the stem, ovate 

 to ovate-lanceolate : perennial by rosulate tufts which 

 form in the fall at the base of the stems : spikelets 

 elliptic to spherical, usually obtuse, sometimes acute, 

 never acuminate. 



I. Paspaloidea. 

 Fourth scale of the spikelet smooth. 

 Terrestrial plants : first scale acute. 

 Aquatic plants : first scale rounded or truncate. 



Spikelets singly disposed, about .S mm. long, the 



first scale rounded or truncate at the apex. 

 Spikelets in pairs, about 2 mm. long, the first scale 

 acute at the summit. 

 Fourth scale of the spikelet transversely rugose. 



II. Capillaria. 



III. HALOPniI.A. 

 IV. ViKGATA. 



V. Ageostoidea. 



VI. DlCHOTOMA. 



1. P. vioUc. 



2. p. pahidivagum. 



."?. /'. hcmitomon. 

 4. P. adspcrsum. 



II. Capillaria. 



Leaf-sheaths pubescent : panicle large, broad. 

 Leaf-sheaths glabrous : panicle small, virgate. 



III. HALOPniLA. 



IV. ViROATA. 



A single species In our range. 

 A single species In our range. 



V. AOItOSTOIDEA. 



Innovations Intravaglnal, hence stems tufted : spikelets 

 not oblique to the pedicels, the apex straight, hence 

 equilateral. 



.5. P. Bartoicensc. 

 6. P. tencrum. 



7. P. amarulum. 



8. P. virgatum. 



