GRAMINEAE (GRASS FAMILY) 



9"; 



larger, glumes many-nerved ; sterile lemma subrigid ; 

 fertile lemma and palea much indurated, acuunnate, 

 margins of lemma neither hyaline nor inrolled. — Erect 

 annuals or perennials with flat leaves. (Name from 

 dfKplKapTTos, doubly fruit-bearing.) 



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

 ing, 3-G 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 

 of the slender subterranean branches. (Milium Amphi- 

 carpon Pursh ; A. Amphicarpon Nash.) — Moist sandy 

 pine barrens, N. J. to Fla. Sept. Fig. 66. 



9. PASPALUM L. 



56. A. Purshii. 

 Sterile spikelet closed x 2. 

 Same wide open x 2. 

 Basal fertile spikelet, 

 partly open x 2. 



P. mucronaium 

 P. dissectum. 



I 



puheficens. 

 P. 3fuhlenhergii. 

 P. atrainineum. 



9. P. Bufihii. 



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. {HaairdXos, a 

 Greek name for millet.) 



a. Eacemes 1-several, 1 terminal and often 1 or more lateral &. 

 b. Khachis membranaceous, 2 mm. or more broad. 



Spikelets 1.5 mm. long, elliptical, pubescent .... 1. 



Spikelets 2 mm. long, oval, glabrous 2. 



&. Ehachis narrow, not membranaceous, less than 1 mm. broad 

 (except in P. Boscianum) e. 

 c. Axillary 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 5. P. ciliatifolium. 



e. Leaves pubescent on one or both surfaces /. 

 /. Spikelets glabrous. 



Leaves densely long-pubescent. 



Culm hirsute below raceme 6. P. 



Culm glabrous 1- 



Leaves puberulent and sometimes sparsely villous . 8. 

 /. Spikelets pubescent ; leaves short-pubescent. 



Culms erect 



Culms prostrate 10. P. psammophilum. 



d. Spikelets 1.5 mm. long. 



Spikelets-glabrous 3. P. longipedunculatum, 



Spikelets pubescent 4, /*, setaceum. 



c. Axillary peduncles none g. 

 g. Spikelets glabrous h. 

 h. Spikelets singly di.«posed 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 12. 



Plants with pubescent sheaths and blades . . . 13. 

 Spikelets 3 mm. long; sheaths papillose-hirsute . . 14. 

 Spikelets 4 mm. long. 



Leaf-blades less than 1.5 dm. long 

 Leaf-blades 2-4 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 sumimt of the culm . 



* Eacemes with a broad, thin-membranaceous, or foliaceous and keeled, rhacMsy 

 2 mm. wide or more, the incurved margins partly inclosing the s^nall 2-rowed 

 spikelets. (Aquatic or nearly so, decumbent or floating .) 

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

 flated ; blades lanceolate, 2.5-15 cm. long, 6-14 mm. loide, scabrous; racemes 

 \0-50. finally spreading ; rhachis extending beyond the spikelets., which are ellip- 



■iKAY'S MANUAL — 7 



11. P. la eve. 



P. (HI g u v fi/oli um. 

 P. p/eNijiilu»u 

 P. circulare. 



16. P. difforme. 

 15. P. florid anum. 



P. la eriglume, 

 P. Boxcianum. 

 P. dihitdlum. 

 P. di.stichum. 



