12 



POACEAE. 



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-sheaths round or but little flattened, not keeled. 

 Fourth scale smooth. 



Rootstocks and stolons naked or with few large 



scales : sand-binders. 

 Rootstocks, at least when young, and stolons covered 

 with numerous small broad acute scales. 

 Fourth scale transversely rugose. 

 Basal leaf-sheaths much compressed, broad, keeled, often 

 equitant. 



II. Halophila. 



III. ViRGATA. 



IV. Maxima. 



Tribe I. PASPALOIDEA. 



Fourth scale of the spikelet smooth. 



Fourth scale transversely rugose ; usually the outer scales of 

 the spikelets with anastomosing veinlets. 

 Branches of the panicle terminated by a spikelet. 



Spikelets broadly obovoid, 2.5-3 mm. long, obtuse or 

 acutish : anastomosing veinlets numerous and prom- 

 inent. 

 Spikelets oval, about 4 mm. long, acute or acuminate : 

 anastomosing veinlets few and faint. 

 Branches extending beyond the spikelet as an awn-like 

 projection. 



Tribe II. HALOPHILA. 



Large grass with acuminate spikelets 5-6 mm. long. 



Tribe III. 

 Stiff grasses with ample panicles. 



VIRGATA. 



V. Agrostoidea. 



1. p. geminatum. 



2. P. fasciculatum. 



3. P. adspersum. 



4. P. Chapmanii. 



5. P. amaruluni. 



6. P. virgatum. 



Tribe. IV. MAXIMA. 

 Tall stout grasses with large leaves and ample panicles. 



7. P. maximum. 



Tribe V. 

 Tufted grasses without rootstocks. 



AGROSTOIDEA. 



8. P. agrostoides. 



J 1^1. P. geminatum Forsk. Stems 6-12 dm. long, usually clothed with sheaths 

 below: leaves glabrous; blades 2. .5 dm. long or less, 6-10 mm. wide: racemes 

 10-20, one-sided, the rachis broadly winged, appressed, 2-3. .5 em. long: 

 spikelets about 2.5 mm. long, ovate, acute, glabrous, singly disposed in 2 rows, 

 the first scale broader than long and clasping the spikelet at its base, truncate 

 at the apex, the fourth scale not transversely wrinkled. — Hammocks and cul- 

 tivated grounds, U. keys, L. keys. — (Bah., Cuha, Ant.) 



35 2. P. fasciculatum Sw. Stems tufted, decumbent, finally branching at the base 

 and often rooting at the lower nodes, glabrous, 3-8 dm. long: leaf-sheaths 

 glabrous or pubescent; blades 2.5 dm. long or less, 8-20 mm. wide, glabrous or 

 pubescent: panicle 1-2 dm. long, its branches ascending or nearly erect: 

 spikelets usually borne in pairs on one side of the branches on frequently 

 bristle-bearing pedicels, brown or green, 2.5-3 mm. long, broadly obovoid, 

 turgid, glabrous, obtuse, the second and third scales with anastomosing veinlets, 

 the fourth scale transversely rugose. — Hammocks, L. keys. — {Bah., Cuha, Ant.) 



i^ 3. P. adspersum Trin. Stems 4-6 dm. tall, decumbent, glabrous, branching 

 below: leaf-.sheaths glabrous; blades 2 dm. long or less, 1.5-2 cm. wide, gla- 

 brous: panicle 1-2 dm. long, its branches ascending or nearly erect: spikelets 

 usually borne in pairs on one side of the branches, green, glabrous or pub- 

 escent, oval, abruptly acuminate, about 4 mm. long, the second and third scales 

 with a few anastomosing veinlets, the fourth scale transversely rugose. — Ham- 

 mocks and cultivated grounds, L. keys. — [E, K.] — {Bah., Cuba, Ant.) 



4. P. Chapmanii Vasey. Glabrous or nearly so: stems 3-6 dm. tall: leaf- 

 blades 3 dm. long or less, 4-6 mm. wide, long-acuminate: inflorescence 1.5-2.5 



