GRAMINEAE (GRASS FAMILY) 



97 



sterile lemma 



subrigid 



larger, glumes many-nerved ; 

 fertile lemma and palea much indurated, acuminate, 

 margins of lemma neither hyaline nor inrolled. — Erect 

 annuals or perennials with flat leaves. (Name from 

 ifxcpiKapTTos, doublij fruit-hfaring.) 



1. A. Purshii Kunih. Annual ; culms erect, branch- 

 ing, 3-6 dm. high; sheaths and blades coarsely hispid; 

 terminal panicle contracted ; spikelets about 4 mm. long ; 

 fertile spikelets solitary, about 6 mm. long, at the ends 

 3f the slender subterranean branches. (Milium Amphi- 

 ".arpon Pursh ; A. Amphicarpon Nash.) — Moist sandy 

 pine barrens, N. J. to Fla. Sept. Fig. 56. 



9. PASPALUM L. 



56. A. Purshii. 



Sterile spikelet closed x z 

 Same wide open x 2. 

 Basal fertile spikelet, 

 partly open x 2. 



Spikelets 1-flowered, plano-convex, nearly sessile, solitary or in pairs, in 2 

 rows on one side of a continuous narrow or dilated rhachis, forming simple spike- 

 like racemes ; spikelets placed with the back of the fertile lemma toward the 

 rhachis ; first glume obsolete (rarely present) ; lemma and palea chartaceous- 

 indurated, margins of the lemma inrolled. — Perennials, with 1-several racemes 

 digitate or racemose at the summit of the culm and branches. {IlacnrdXos, a 

 Greek name for millet. ) 



a. Raceme? 1-several. 1 terminal and oft«n 1 or more lateral &. 

 If. Rhachis membranaceous, 2 mm. or more broad. 



Spikelets 1.5 mm. long, elliptical, pubescent .... 



Spikelets 2 mm. long, oval, glabrous 



b. Rhachis narrow, not membranaceous, less than 1 mm. broad 

 (except in P. Boscianum) c. 

 c. AxUlary peduncles 1 or more from uppermost sheath ; leaves 

 ciliate on the margin d. 

 d. Spikelets 2 mm. long e. 



e. Leaves glabrous on both surfaces ..... 

 e. Leaves pubescent on one or both surfaces f. 

 f. Spikelets glabrous. 



Leaves densely long-pubescent. 



Culm hirsute below raceme 



Culm glabrous 



Leaves puberulent and someMmes sparsely villous . 

 f, Spikelets pubescent ; leaves short-pubescent. 



Culms erect 



Culms prostrate • . 



d. Spikelets 1.5 mm. long. 



Spikelets glabrous 



Spikelets pubescent 



C. Axillary peduncles none g. 

 g. Spikelets glabrous h. 

 h. Spikelets singly disposed so as to appear in 1-2 rows. 

 Spikelets 2.5 mm. long. 



Plants glabrous or sparingly pilose. 

 Leaf-blades of culm 1-2" dm. long; racemes 3-5 



cm. long 



Leaf-blades of culm 2-4 dm. long ; racemes 8-10 

 cm. long ........ 



Plants with pubescent sheaths and blades . 

 Spikelets 3 mm. long; sheaths papillose-hirsute . 

 Spikelets 4 mm. long. 

 Leaf-blades less than 1.5 dm. long .... 



Leaf-blades 2-i dm. long 



h. Spikelets in pairs so as to appear in four rows. 



Spikelets stramineous at maturity 



Spikelets dark brown at maturity 



g. Spikelets ciliate 



a. Racemes a pair at the summit of the culm .... 



1. P. mitcronaium. 



2. P. dissecium. 



5. P. ciliatifolium. 



6. P. puhescens. 



T. P. MuhJenhergii, 



8. P. fiirarainenra. 



9. P. Bmhii. 



10. P. psammophilum. 



3. P. longipedunculatv/m 



4. P. setaceinn. 



11. P. laeve. 



12. P. angustifolium 

 1-3. P. pleniinlum. 



14. P. circular e. 



16. P. difforme. 



15. P. Jloridanum. 



17. P. laeriglume. 



18. P. BoHcianum. 



19. P. dilatatum. 



20. P. difftichurn. 



* Bacemes with a broad, thin-memhranaceous, or foJinceons and keeled, rhachis, 

 2 mm. wide or more, the incurved margins partly inclosing the small 2-rowed 

 spikelets. (Aquatic or nearly so. decumbent or lioating.) 



1. P. mucronatum Muhl. Sheaths papillose-hirsute or nearly smooth, in- 

 flated ; blades lanceolate, 2.iv-15 cm. long, 6-14 mm. loide. scabrous; racemes 

 10-50, finally spreading ; rhachis extending beyond the spikelets, which are elUp- 



gray's manual — 7 



