Thk Grasses ok Tknxksskk. 57 



and is only found here in cultivation or perhaps sprinj^^injj up from 

 seed on land where cultivated the season previous. The (lerman 

 differs from the Italian Millet in having a more dense or compact 

 and usually erect panicle or "head." 



11. CENCHRUS Linn. Sp. PI. 1049 (1753). 



Spikelets hermaphrodite. One-flowered (rarely with a male 

 flower below the perfect terminal one), one to four toj^ether, with 

 an ovoid or globular involucre of rigid more or less connate bris- 

 tles, forming spiny burs or false capsules, these sessile or nearly so 

 in simple terminal spikes or racemes, falling off with the spikelets. 

 (ilumes as in Panicum, awnless. Grain free within the slightly- 

 hardened fruiting glume and palea. 



Annual or perennial grasses with spreading or erect culms, 

 bearing few or many more or less crowded "burs" in terminal 

 spikes. 



Species about twelve, in the tropical and warmer temperate re- 

 gions of both hemispheres. One species introduced in Tennessee. 



I. Cenchrus tribuloides Linn. Hedgehog- or Bur-grass. 

 Plate XVII. Figure 65. 



Annual, with spreading or ascending much-branched culms, 

 rarely a foot high, somewhat compressed. Leaves flat or simply 

 folded, about six inches long, acute, finely serrulate along the mar- 

 gins; sheaths generally much exceeding the internodes, hairy along 

 the margins and at the throat. Burs containing the spikelets, six 

 to twenty, nearly globose, covered with strong and more or 

 less pubescent barbed spines, becoming very hard at maturity 

 and readily falling off. Along the Mississippi river. July — 

 August. 



Reported by Dr. Gattinger as growing along the sand}" banks of 

 the Mississippi river. It grows only in sandy soils, but in such 

 lands it may become a terrible pest, and every pains should be 

 taken to exterminate it wherever seen, 



12. PENNISETUM Pers. Syn. I. 72. (1S05). 



Spikelets solitary or two to three together, subtended by an in- 

 volucre of one to many bristles, which are often plumose and fall 

 otf with the spikelets at maturity: inflorescence racemose or dense 

 and spike-like. Glumes four, the first empty and smaller than the 

 others; the second usually as long as the spikelet, empty ; the third 

 empty or with a palea or with a staminate flower; the fourth or 

 terminal enclosing a pistillate or hermaphrodite flower and palea. 

 Stamens three. Styles distinct or more or less connate below; 

 stigmas plumose. Grain included in the rigid fruiting glume and 

 palea, free. Annual or perennial grasses, with simple or branched 

 culms, flat leaves, and usually spike-like panicles terminal on the 

 culm or its branches. 



Species about forty, chiefly natives of the tropical and sub-trop- 



