GRAMINEAE 



17 



2. S. linearis ( Krock. ) Nash. Smooth Crab-grass. Culms decum- 

 bent : leaves short, V-3^ long, glabrous : spikes 2-6 : spikelets V^ long : 

 first glume AYanting : second glume as long as flowering one, hairy. — Com- 

 mon in sandy fields, especially along the Missouri River. Jnly-October. 



3. S. sanguinalis (L.) Dulac. Crab-grass. Culms erect, ascending 

 or spreading, l°-3° long : leaves 2^-6^ long : spikes 3-12, spreading : 

 spikelets ly^ long : lowest glume i^resent : second glume half as long as 

 the flowering one. — Growing everj'where in fields. July-October. 



8. PANICUM L. Panic Gra.ss. 

 Spikelets with one pistillate and sometimes one additional staminate 

 flower. Glumes four, the three lower merabranons, the two lower empty, 

 the third usuallj' empty or sometimes bearing a staminate flower. Fourth 

 scale thick and shiny, inclosing a similar palet. 



Some or all the flowers awned. 1. P. C'Us-GaUi. 



Flowers never awned. 



All leaves similar ; panicle elongated. A. 



Basal leaves .shorter and broader than the culm 



leaves ; jjaniele short. B. 



A. 

 Smooth throughout. 



Spikelets 2'^ long. 12. P. virgatum. 



Spikelets \"-\\" long or less. 14. P. proUferum. 



Spikelets §'^ long. 2. P. agrostoides. 



More or less pubescent, especially the lower 

 sheaths. 

 Spikelets 2^^ long or more. 13. P. miliaveum. 



Spikelets IV^ long or less. 



Panicle bearded in the axils. 17. P. cngnnium. 



Panicle not bearded in the axils. 



Culms stout anH much branched. 15. P. capillare. 



Culms slender, branching only from base. IG. P. fledle. 



B. 

 Culm leaves long and linear. 

 Culm leaves lanceolate or broader. 

 Spikelets 1^^ long or less. 

 Leaves almost glabrous. 

 Leaves pubescent. 



Axis of panicle long-pilose. 10. P. lanuginoRum. 



Axis of panicle almost smooth. 9. P. unciphylhim. 



Spikelets more than 1^^ long. 



Culm leaves broad and clasping at base. 

 Sheaths papillose-hispid. 

 Sheaths not papillose-hispid. 



Sheaths hairy. 3. P. 



Sheaths glabrous. 4. P. 



Culm leaves lanceolate, hardly clasping at 



base. 



Spikelets nearly glabrous. 6. P. 



Spikelets very hairy. 7. P. 



1. P. Crus-Galli L. Barnyard Grass. 



11. P. j)erlongiim. 



8. P. sphaerocarpon. 



5. p. chtndesiinum. 



Porierianuin. 

 macrocarpon. 



high, with 

 2 



6. P. Scrihnerianum. 



7. P. Liehergii. 



A coarse grass l°-5° 

 long rough leaves : spikelets imbricated, making the 5-15 



