GRAMINEAB 885 



1. C. tribuloldes, L. Culms branched at base, geniculate, ascending, 

 or procumbent ; spike oblong ; involucre spinose, pubescent, split 

 on one side. 

 TEIBULUS-LIKE CENCHRUS. Bur-grass. Hedgehog-Grass. 



Annual. Culms 9 to 18 inches long, smooth. Leaves 3 to 8 inches long; sheaths 

 loose, smooth ; ligule beard-like. Spike terminal, consisting of 6 to 12, or more, 

 alternate involucrate heads, or clusters ; rachis angular, flexuose, slightly sca- 

 brous; involucre urceolate, or subglobose, laciniate, armed externally with rigid, 

 subulate, scabrous spines, villous within, embracing 1, 2, or 3 spikelets ; sterile 

 floret mostly staminate. 

 Hob. Old fields. Nat. of the South, fl. Aug. Fr. Sept. 



Obs. This pestilent grass is, happily, yet rare in our County; 

 but is gradually extending itself, and, if not vigilantly watched, 

 will one day be found a great nuisance, around our dwellings. It 

 is very abundant in the sandy districts of New Jersey ; but whether 

 indigenous there, I cannot say. 



TRIBE 8. SACCHA^REAE. 



Paleae of the fertile florets membranaceous, always thinner and more delicate 

 than the (often indurated) glumes, frequently awned at apex ; spikelets usually 

 in pairs, or threes, spiked, or panicled, some of them entirely sterile (m&noicous, 

 or polygamous). 



1. SPIKELETS MONOICOUS : Pistillate spikelets imbedded in the rachis of the contin- 

 uous spike, or in its separable joints. 



506. ZE X A, L. 



[Gr. Zao, to live; from the sustenance it affords to animal life.] 

 STAMINATE SPIKELETS in terminal, fascicled, spicate racemes, 2- 

 flowered; glumes herbaceous, pubescent; paleae membranaceous, 

 awnless ; stamens 3 ; anthers linear, erect ; scales 2, collateral, fleshy, 

 glabrous. PISTILLATE SPIKELETS sessile, 2-flowered (the lower one 

 abortive), in dense continuous spikes, which terminate short, nodose, 

 axillary branches, the spikes enveloped by the sheaths of abortive 

 leaves, called husks; glumes fleshy-membranaceous, very broad, 

 ciliate, the lower one emarginately 2-lobed; paleae fleshy-mem- 

 branaceous, the abortive floret with 2 paleae. Ovary roundish- 

 ovoid ; style capillary, very long, exserted from the envelopes of the 

 spike,!" pubescent at summit, and mostly bifid (stigmas?). Grain 

 usually crowded, and then compressed, cuneate, or roundish- 

 reniform, with a shallow groove on the upper side containing the 

 embryo, the base imbedded in the persistent glumes and paleae. 

 Annual : culm stout, solid with pith ; pistillate spikelets in 8 to 12 

 longitudinal rows, on the thick subcylindric rachis, the rows always 

 in approximated pairs, before the spaces are filled by their growth ; 

 spikes (or ears) 1 to 3 or 4 (rarely more usually 2) on a culm. 



1. Z. MXvs, L. Leaves flat, linear-lanceolate, acuminate, with a 

 broad midrib channelled above. 

 Indian Corn. Maize. 



Culm 4 to 15 feet high, and about an inch, or inch and a half, in diameter, sim- 

 ple (often producing branches, or suckers, at base), nodose, semi-terete, or with a 

 broad shallow channel, on alternate sides, between the nodes. Leaves 2 to 3 feet 



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