WORLD’S TRIBES AND LEADING GENERA 57 
42. Brachypodium. Spikelets on extremely short pedicels, so 
as to appear sessile on the rachis, the inflorescence spikelike (figs. 
25 and 33). Flowering glumes awned. 
lt is important to note carefully the generic characters of Poa, 
Glycerta, and Festuca. These three genera are all well repre- 
sented in our flora, and many of the species are very abundant ; 
inattention to the characters which distinguish these genera one 
from another would therefore lead to confusion. 
Tribe HORDEE&. Spikelets sessile, in notches 
or excavations of the simple rachis (inflorescence 
truly spiked). A very simple character, and there 
is no possibility of mistaking this tribe. The notched 
rachis is well shown in fig. 39. There are three 
sub-tribes. cad ‘ 
Sub-tribe TRITICEA. Spikelets one in each notch 
of the rachis, many-flowered. 
Genus 43. Lolium, Back of the glumes towards 
the rachis (spikelets edgewise). 
44. Agropyrum. Margins of the flowering 
glumes against the rachis (spikelets broadside) (fig. 
31). ; 
Sub-tribe LEPTUREA. Spikelets one in each 
notch, 1-, rarely 2-flowered. 
45. Lepturus. Empty glumes two in the British 
species (fig. 29). 
46. Mardus. Empty glumes absent. 
Sub-tribe ELYME&. Two or three spikelets at 
each excavation. 
47. Hordeum. Spikelets containing one flower 
‘and a rudiment, many-awned. 
48. Elymus. Spikelets 2- or more-flowered, not 
awned in the British species. Auoaa— Spike 
So far, we have only considered the British tribes (yyy “oudyare: 
and genera; to have incorporated with them the spikelets remov- 
exotic tribes would only have served to confuse the °¢ from lower 
2 i . " part to show (g) 
beginner. The following complete list (which the notches or excav- 
student may ignore altogether if he chooses, or at ations of the 
least until he has mastered the British genera) of ™°"* 
tribes, and the more important genera, is given be- 
cause many of the latter are mentioned in the chapters on Dis- 
tribution and Uses. 
Series A. PANICACEA, described in the preceding pages, is 
divided into six tribes, viz. : : 
PANICE#, characters already given. This tribe comprises 
thirty genera, the leading ones being Panicum, Paspalum, Pennt- 
setum, Olyra, 
MAYDE#. Spikelets always unisexual, male ones in the upper 
part ot the inflorescence, female spikelets in the lower part; or 
(in Parana) male spikelets surrounding the females at each node. 
This is a tribe of eight small genera, tropical or American, in- 
cluding Zea Mazs (maize) and Cotx lachryma. 
