96 GEAMINEAE (GKASS l^AMILY) 



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



densely short-villous between the nerves, as lung as the dark hrown fertile lemma. 



{Panicum lineare Krock ; P. glabrum Gaud.) — Cultivated and 



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



l| from Eu.) Fig. 54. 



W 4. D. ser6tina Miclix. Extensively creeping, forming dense 



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



Ri Ti V -f wide, pilose on both surfaces; racemes 3-8, at the apex of 



SniketotTr"' ascending branches (1-3 dm. high), 3-10 cm. long; spikeleta 



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



nerves; the glume scarcely j as long as the pale fertile lemma. (_Panicum 



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



•1- -1- 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 ram. 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 J as long as the pale ar grayish fertile lemma. 

 (Panicumlj.; Syntherismafimbriata'Sa.sh.) — Cultivated m. D. eanguinalis. 

 and waste grounds, throughout our range, and southw. Part of inflorescence x%. 

 Aug.-Oct Very variable. (Nat. from Eu.) Eio. 56. Spikelets xS. 



7. LEPTOL6mA Chase 



Spikelets l-flowered, fusiform, solitary on long capillary S-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, vfith 

 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 XeirrSs, delicate, and Xffl/ia, border, in reference to the 

 hyaline margins of the lemma.) 



1. L. cognktum (Schultes) Chase. (Fall Witch Grass.) Pale green, much 

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

 lower sheaths pilose, 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 tht. 

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

 glume and sterile lemma with a stripe of oppressed silky pubescence between the 

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

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

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

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



8. AMPHICAkPON Eunth 



Spikelets 1-floivered, of 2 kinds, one in a terminal panicle, perfect but not 

 fruitful, the other subterranean, clelstogamous, on slender leafless stems at the 

 bass of the culm ; the first glume of the atrial spikelets variable in size or obso- 

 lete ; the second and the sterile lemma subequal ; lemma and palea indurated 

 margins of lemma neither hyaline nor inrolled : clelstogamous spikelets much 



