GRASS FAMILY 335 



x. Bristles downwardly barbed 



(x) Spikelets 4-10 mm. long; bristles us- 

 ually 6 ; styles 3 S. atrovirens 

 ( v ) Spikelets 3-4 mm. long; bristles 4; 



styles 2 5\ microcdrpus 



y. Bristles smooth, 6; Spikelets 6-10 mm. 



long ; styles 3 5. linedtus 



POACEAE GRASS FAMILY 



Sepals and petals none, occasionally represented by bristles or scales, 

 stamens 1-6, usually 3, styles usually 2, ovary 1-celled, fruit a seed-like 

 grain ; flowers perfect or sometimes monoecious or dioecious, or reduced to 

 1-2 scales, with 1-3 minute scales called lodicules, usually enclosed in 2 

 scales, the inner called the palet, the outer the lemma; spikelets 1-many- 

 flowered, usually enclosed at the base by 2 scales or glumes, in racemes, 

 panicles or spikes ; leaves mostly long-linear, sheathing, the sheaths usually 

 split to the base and bearing at the top a papery or thickened ring called a 

 ligule ; annual or perennial herbs. 



1. Spikelets sessile in 2 rows in a one-sided or zig- 

 zag spike 



a. Spikelets in one-sided spikes 



(1) Spikelets dioecious, the staminate spikes 



one-sided, the pistillate ball-like BULBILIS 



(2) Spikelets perfect, the spikes alike 



(a) Spikes long and narrow, thread-like 



x. Spikes in a raceme-like cluster SCHEDONNARDUS 



y. Spikes in a digitate cluster DIGITARIA 



(b) Spikes not long and thread-like 



x. Plains grasses with mostly horizontal or 



hanging spikes BOUTELOUA 



y. Meadow or swamp grasses with erect 



or ascending spikes 



(x) Spikes long, the axis extending be- 

 yond the spikelets SPARTINA 

 (y) Spikes short, the axis not extended BECKMANNIA 



b. Spikelets alternating on opposite sides of a zig- 



zag, usually jointed axis 



(1) Spikelets usually single at each joint 



(a) Spikelets with the face toward the axis AGROPYRUM 



(b) Spikelets with the edge toward the axis LOLIUM 



(2) Spikelets usually 2-6 at each joint 



