GRAMFNEAE, the Grass Family 



Grasses, with linear or narrow sheathing leaves, and very small 

 flowers without perianth in the axils of chaffy bracts, appearing in 

 late spring and summer. 



Of the large number (over 150) of grasses in Michigan, only the 

 commonest are included here, and the student is referred to the Man- 

 uals for a full treatment of them. 



Their classification depends chiefly upon the structure and ar- 

 rangement of the spikelets. These consist typically of a short axis, 

 the rachilla, almost or quite concealed by several chaffy bracts. The 

 two lower bracts are termed glumes, and have no flowers in their 

 axils. Above the glumes are two or more other bracts, the lemmas. 

 In the axil of each lemma, and usually concealed by it, is a smaller 

 bract, the palea, and between the lemma and the palea is a single 

 flower. The number of flowers in a spikelet is therefore normally 

 equal to the number of lemmas. The spikelets are grouped in racemes, 

 spikes, or panicles of various size. 



la. Spikelets one-flowered 2. 



Ib. Spikelets with 2 or more flowers 24. 



2a. Spikelets grouped into dense solitary cylindrical spikes 3. 

 2b. Spikelets arranged in panicles or in panicled spikes 8. 



3a. Spikelets without awns or bristles, or with short awns not more 



than 3 mm. long 4. 

 3b. Spikelets with awns 2 5 cm. long, terminating the bracts 



Squirrel-tail, Hordeum jiibatuni. 

 3c. Bracts of the spikelet without terminal awns, but the spikelets 



with one or more long bristles arising from their base 6. 



4a. Spike-like panicle thickened in the middle, more than 1 cm. 

 thick Beach Grass, Ammophila arenaria. 



4b. Spike little or not at all thickened in the middle, less than 

 1 cm. thick 5. 



5a. Lower bracts awned; stem erect, unbranched 



Timothy, Phleum pratense. 

 5b. Lower scales unawned; stem branched at the base 



Floating Foxtail, Alopecurus g-eniculatus. 

 6a. Bristles 5 or more at the base of each spikelet 



Yellow Foxtail, Setaria arlauca, 

 6b. Bristles 1 3 at the base of each spikelet 7. 



7a. Spikelets about 2 mm. long; bristles not much longer, green 



Green Foxtail, Setaria viridis. 



7b. Spikelets about 3 mm. long; bristles much longer, usually purple 



Millet, Setaria italica. 



8a. Spikelets numerous, in long slender symmetrical spikes 9. 

 8b. Spikelets in panicles, racemes, or loose spikes 13. 



