96 GRAMINEAE (GRASS FAMILY) 



spikelets solitary or in 2's, 2.2 mm. long ; the glume and sterile lemma equals 

 densely short-villous between the nerves, as long as the dark hrownfertUc lerarua. 



{Panicnm Uneare Krock ; F. glahrum Gaud.) — Cultivated and 



waste ground, N. S. to S. Dak., and southw. Aug.-Oct. (Nat. 



from Eu.) Fig. 64. 



4. D. ser6tina Michx. Extensively creeping, forming dense 



mats ; the crowded sheaths pilose y blades 2-8 cm. long, 4-7 mm. 

 H T) h f wide, pilose on both surfaces; racemes 3-8, at the apex ot 

 ' Sr>ikelet°xr^" ^scending branches (1-3 \lm. high), 3-10 cm. long; spikelets 



mostly in 2's, 1.6 mm. long, sparsely pubescent between the 

 nerves; the glume scarcely \ as long as the pale fertile lemma. {Panicnm 

 Trin.) — Low sandy ground near the coast, s. Pa., Del., and southw. Juue-Aug. 



-»- •»- Pedicels sharply angled; first glume present, minute. 



5. D. sanguinXlis (L.) Scop. (Crab Grass.) Culms erect or ascending 

 from a decumbent often creeping base, 3-12 dm. long ; 

 nodes and sheaths more or less papillose-hirsute ; blades 

 lax, 5-12 cm. long, 4—10 mm. wide, scabrous, often more 

 or less pilose ; racemes 3-12, subfasciculate, 5-18 cm. 

 long ; spikelets in pairs, 3-3.5 mm. long, usually appressed- 

 pubescent between the smooth or scabrous nerves ; second 

 glume about \ as long as the pale or grayish fertile lemma. 

 (PanicumJj.; Syntherisma fimbr lata ^a,sh.) — Cultivated 5,-,. d. sanguinalis. 

 and wa.ste grounds, throughout our range, and southw. Part of intiorescence X14. 

 Aug.-Oct Very variable. (Nat. from Eu.) Fig. 55. Spikelets x 3. 



7. LEPTOLOMA Chase 



Spikelets 1 -flowered, fusiform, solitary on long capillary 3-angled pedicels; 

 first glume obsolete or very minute, the second 3-nerved, nearly as long as the 

 5-7-nerved sterile lemma ; fertile lemma cartilaginous-indurated, papillose, witli 

 a delicate hyaline margin not inrolled. inclosing a palea of like texture ; grain 

 free within the lemma and palea. — Tufted perennials, with flat leaves and very 

 diffuse terminal panicles, which break away at maturity and become tumble- 

 weeds. (Name from Xewros, delicate, and \Q/xa, border, in reference to the 

 hyaline margins of the lemma.) 



1. L. cognatum (Schultes) Chase. (Fall Witch Grass.) Pale gi'een, much 

 branched at the base, erect or geniculate below, very brittle, 3-7 dm. high ; 

 lower sheaths j^ilose, the upper usually glabrous ; ligule membranaceous, 1 mm. 

 long ; blades 5-8 cm. long, 4-6 mm. wide, rather rigid, usually glabrous, scabrous 

 on the margins ; panicle \-^ the entire height of the plant, short-exserted, very 

 diffuse, as broad as long or broader ; the capillary scabrous subflexuous 

 branches at first ascending, soon widely spreading, naked below, pilose in the 

 axils ; spikelets on scabrous pedicels, 1-4 cm. long, acuminate, 2.7-^3 mm. long ; 

 glume and sterile lemma icith a stripe of appressed silky pubescence betioeen the 

 nerves and on the margins, or the hairs becoming loose and spreading esperiaUy 

 on the margins, very variable in the same panicle ; fruit acuminate, chestnut, 

 the margins of the lemma white. (Panicum Schultes ; P. autiimnale Bosc.) 

 -^ Dry soil and sand hills, N. H. to Fla. ; 111. to Minn., southw. and south westw. 



8. AMPHICARPON Kunth 



Spikelets l-flo*vered, of 2 kinds, one in a terminal panicle, perfect but not 

 fruitful, the other subterranean, cleistogamous. on slender leafless stems at the 

 base of the culm ; the first glume of the aerial spikelets variable in size or obso- 

 lete ; the .second and tlie sterile lemma subequal ; lennna and palea indurated, 

 margins of lemma neither hyaline nor inrolled ; cleistogamous spikelets umch 



