Tm: (Jkassks ok Tknnkshke. 68 



trihuteJ chroiig-hoiit nil tlie temperate and colder rejj^itjns of the 

 world and many occur within the tropics. The j^enus Ai^rostis, from 

 which the tribe derives its name, and from which comes the word 

 Aijrostolo^ist, has about loo species; found in all parts of the 

 world, especially in the north temperate zone. vSome of our most 

 important meadow jjrasses — notably Herd's-^rass aiid Timothy — 

 belon<^ to this tribe. 



18 ARISTIDA Linn. Sp. PI. .S2 (i753)- 



Spikelets one-tlowered, on long or short slender pedicels in ter- 

 minal, more or less expanded panicles; rachilla articulated above 

 the empty illumes and produced into a hard obconical hairy callus 

 below the lloral glume, but not extending beyond it. Glunies 

 three, the first two empty, more or less unequal, acute or bristle- 

 pointed, slightly keeled; the third or flowering glunje firmer in 

 texture than the outer ones, closely rolled around the flower, the 

 usually short palea terminating in a trifid awn. Grain slender, 

 tightly enclosed by the hardened fruiting glume, but free from it. 



Tufted narrow-leaved grasses, chiefly growing in dry sandy or 

 sterile soil. 



Species about one hundred, in all the warmer regions of the 

 world. wSome thirty-eight species are recorded as growing within 

 the United States, chiefly in the southern portions. The following 

 are found in Tennessee: 



KKV TO THE SPECIES. 



I. Awns very unequal in length 2 



1. Awns nearly of equal length 4 



2. Spikelets 6 to 10 lines long, the middle awn an inch long and 



abruptly recurved i. A. r.amosissi.ma. 



2. Spikelets 2 to 4 lines long, in slender spikes or racemes . . 3 



3. Middle awn flexuose or coiled near the base, and soon re- 



flexed 2. A. DICHOTOM.A. 



3. Middle awn not flexuose or coiled near the base, divergent 



3. A. GR.\CILIS. 



4. Spikelets 9 to 12 lines long, in loosely few-flowered racemes, 



awns I to 2 inches long, more or less divergent .... 



6. A. OLIG.ANTH.A. 



4. Spikelets 4 to 5 lines long, in many-flowered spike-like pan- 



icles 5 



5. First glume longer than the second, awns much longer than 



the glumes 4. A. purpuraslens. 



5. First glume shorter than the second, awns about the length 

 of the glumes 5- A. strict.^. 



I. Aristida ramosissima Engelm. 



Plate XVIIT. Figure 72. 



A low, very much-branched grass six to fifteen inches high, with 

 numerous loosely few-flowered spikes or racemes. Empty glume'* 



