BRITISH TRIBES AND GENERA 55 
_ Insome species of Azra and Deschampséa, the twist of the awn 
is scarcely perceptible. 
23. Tvrisetum. Spikelets small, much flattened laterally, 2- to 
6-flowered ; flowering glume keeled, with a long dorsal awn, and 
tipped with two short awns or sete. 
24. Avena. Spikelets large, 2- to 6-flowered ; flowering glumes 
Pa ‘aaa on the back (keelless), and with a long dorsal awn 
g. 20). 
In the next two genera, the spike- 
lets contain two flowers, one of which 
is staminate (with stamens only). 
25. Holcus. Lower flower bi- 
sexual, its glume awnless; upper 
flower staminate, its glume awned 
(fig. 8). 
26. Arrhenatherum. Lower flower 
staminate and its glume awned; 
upper flower bisexual (the reverse 
of Holcus). 
Tribe CHLORIDE&. Spikelets 
sessile in two rows on one side of 
the rachis, I- or more-flowered, with 
a terminal rudiment ; glumes keeled, 
and spikelets compressed laterally : 
rachis neither notched nor jointed. 
The inflorescence is very like that 
of some Panicacee, but the rudi- 
ment is terminal, and the empty 
glumes are persistent. 
Genus 27. Cynodon. Rachis 
compound, spikes fingered ;_ spike- 
lets 1-flowered. 
Tribe FESTUCE&. Spikelets con- 
taining two or many flowers, and 
often aterminal rudimentary glume ; 
Fic. 37.—Deschampsia caespitosa; 
. left-hand figures enlarged—the lower 
awn absent, or terminal or subter- a spikelet, the upper a flowering glume, 
minal, not twisted, straight. There etc., showing short straight dorsal 
awh, 
are eight sub-tribes, of which six are 
represented in Britain. 
Sub-tribe TRIODIE&. Spikelets 2- or more-flowered; flower- 
ing glumes tipped with three teeth, lobes or short awns. 
Genus 28. Z?iodia. Flowering glumes with three broad teeth. 
Sub-tribe ARUNDINEZ. Spikelets 2- or more-flowered; flower- 
ing glumes enveloped in long silky hairs growing on the rachilla. 
29. Phragmites. Lowest flower staminate (fig. 38). 
Sub-tribe SESLERIEZ. Inflorescence spikelike, or capitate (in 
the form of a head), with bracts (empty glumes) either at the base 
or forming sterile spikelets. 
30. Sesleria. Pedicels of lower spikelets sheathed by a simple 
bract or empty glume (fig. 21). 
