558 GRAMINE^E. (GRASS FAMILY.) 



less. Glumes 2, membranaceous, very unequal ; the larger upper one with a 

 spreading awn or tubercle on the back. Palese of the perfect flower membrana- 

 ceous ; the lower one awned below the apex, and densely ciliate on the margins. 

 Stamens 3. Ovary smooth. Styles terminal : stigmas elongated, plumose, with 

 simple hairs. Grain free. 



1. C. Americanum, Spreng. Root pungent; culm (2 -3 high) rough, 

 like the narrow leaves; spike at length recurved or coiled (3' -4' long) ; upper 

 glume granular on the back; the stout awn spreading horizontally. (Monocera 

 aromatica, Ell) Low pine barrens, Florida to North Carolina. July and 

 Aug. H. 



21. DACTYLOCTENIUM, Willd. CROWFOOT-GRASS. 



Annual creeping or spreading branching grasses, with flat leaves and digitate 

 rarely single spikes. Spikelets 2 - several-flowered, crowded on one side of the 

 flattened rachis ; the uppermost flower imperfect. Glumes 2, compressed-keeled, 

 membranaceous ; the upper (exterior) awn-pointed. Pales 2, boat-shaped, 

 pointed. Stamens 3. Stigmas plumose, with branching hairs. Grain round- 

 ish, rugose, free. 



1. D. JEgyptiacum, "Willd. Culms ascending from a creeping base; 

 leaves fringed ; spikes commonly 4, awn-pointed ; spikelets 3-flowered. (Eleu- 

 sine? cruciata, Ell.} Cultivated ground, common. Introduced. Culms nu- 

 merous, 1 high. Spikes 1'- 2' long. 



22. ELETJSINE, Gart. 



Characters chiefly of Dactyloctenium, but the narrower glumes and palese 

 obtuse and awnless. Stigmas plumose, with simple hairs. Spikelets closely 

 imbricated. Low annuals. 



1. E. Indica, Gaert. Cultivated ground, very common. Introduced. 

 Culms (6' -18' high) flattened; leaves flat; spikes 2 -several, the lower ones 

 sometimes scattered (2' -4' long) ; spikelets 6-flowered. 



23. LEPTOCHLOA, Beauv. 



Flat-leaved grasses, with the numerous spikes disposed in a terminal raceme. 

 Spikelets sessile, loose on one side of the elongated filiform rachis, 3 - many- 

 flowered. Glumes 2, membranaceous, unequal, keeled. Paleae 2, membrana- 

 ceous ; the lower one longer than the upper, 3-nerved, awned or unawned. 

 Stamens 3. Grain oblong, free. 



1. LEPTOCHLOA PROPER. Loiver palea unawned. 

 1. L. mucronata, Kunth. Culms 2 -3 high; sheaths of the broad (4"- 

 6" wide) rough leaves hairy; spikes numerous, in an elongated raceme, 2' -4' 

 long, spreading; spikelets minute, 3 - 4-flowered ; glumes mucronate, longer or 

 shorter than the flowei's ; lower palea smooth, emarginate. (Eleusine mucro- 

 nata, Michx.) Cultivated fields, Florida, and northward. Aug. - Sept. 



