POACEAE 49 
(ligule), naked or sometimes hairy, rarely wanting, occurs at the sheath-orifice. 
Inflorescence of spikes, racemes, or panicles, composed of spikelets, these con- 
sisting of 2-many 2-ranked imbricated bracts (scales), usually the lower 2, and 
occasionally the succeeding 2-4 scales also empty, rarely all the scales flower- 
bearing. One or more of the upper scales, except sometimes the terminal one, 
bearing an axillary flower surrounded by a bract-like organ (palet), which is 
placed opposite to the scale and with its back to the axis (rachilla) of the 
spikelet, usually 2-nerved or 2-keeled and awnless, rarely 1-nerved or awned ; 
the palet is sometimes present without the flower and vice versa; the rachilla 
is often thickened and appears as a hard projection (callus) at the base of the 
scale. Flowers perfect, staminate, or pistillate, subtended by 1-3 minute 
scales (lodicules). Stamens 1-6, rarely more, usually 3. Anthers 2 celled, 
versatile. Ovary 1-celled, 1-ovuled. Styles 1-8, commonly 2, distinct or more 
or less united, rarely wanting. Stigmas hairy or plumose. Fruit a seed-like 
grain (caryopsis), sometimes nut-like. Endosperm starchy. [Gramineae Juss.] 
A. Spikelets falling from the pedicel entire (see also nos. 58, 61, 62, 68 and 76 of section B), naked, or en- 
closed in bristles or a bur-like involucre, or immersed in the internodes of a readil disarticulating 
rachis, 1-flowered, or if 2-flowered the lower flower staminate ; no upper empty scales: rachilla not 
extending beyond the uppermost scale. 
Spikelets round or somewhat dorsally compressed ; empty scales manifest: hilum punctiform. 
Flowering scale and palet hyaline, thin, much more delicate in structure than the thick-mem- 
branous to coriaceous empty scales. 
Spikelets unisexual, the pistillate borne in the lower, the E 
staminate in the upper, part of the same spike. TRIBE I. MAYDEAE. 
Spikelets in pairs, one sessile, the other pedicellate, the 
former perfect, the latter sometimes perfect, more com- 
monly with a staminate flower, often empty or reduced 
to one or two scales, or occasionally wanting; both i ree 
spikelets pedicellate in nos. 2 and 6. TRIBE II. ANDROPOGONEAE 
Flowering seale, at least that of the perfect flower, similar in 
texture to the empty scales, or frequently thicker and 
firmer, never hyaline and thin. 
Flowering scale and palet membranous. 
Inflorescence spicate: spikelets deciduous singly or in MTM 
groups, the first scale usually larger than the rest. TRIBE III. ZOYSIEAE. 
MV vede ee v eap dc $ dg LUE Eom rid 
rom the ultimate branches, the first scale usually 3 
smaller or narrower than the rest. TRIBE IV. TRISTEGINEAE. 
Flowering scale and palet chartaceous, cartilaginous, or 
coriaceous, very different in color and appearance 
from the remaining scales. TRIBE V. PANICEAE. 
Spikelets much compressed laterally ; empty scales none or rudi- 3 
mentary: hilum linear. TRIBE VI. ORYZEAE. 
B: Spikelets with the empty scales persistent, the rachilla hence articulated above them Paor them 
in nos. 58, 61, 62, 68 and 76 and the spikelet falling entire), 1-many-flowered ; frequently the upper 
scales are empty : rachilla often produced beyond the uppermost scale. 
Stems herbaceous, hence annual: leaf-blade sessile, not articulated with the sheath. 
Spikelets borne in open or spike-like panicles or racemes, usually upon distinct and often long 
pedicels. 
Spikelets 1-flowered. 
Empty scales 4: palet 1-nerved. TRIBE VII. PHALARIDEAE. 
Empty scales 2 (rarely 1): palet 2-nerved. TRIBE VIII. AGROSTIDEAE. 
Spikelets 2-many-flowered. 
Flowering scales usually shorter than the empty ones, 2 
the es dorsal and usually bent. TRIBE IX. AVENEAE. 
Flowering seales usually bone An empty en ses 
i ight, rarely dorsal, so 
Rd Ri puis d | TRIBE XI. FESTUCEAE. 
Spikelets in two rows: : 
On one side of the continuous axis, forming one-sided spikes 
or racemes. TRIBE X. CHLORIDEAE. 
On opposite sides of an axis which is often articulated, 
orming equilateral spikes. TRIBE XII. HORDEAE. 
Stems, at least near the base, woody, hence perennial: leaf-blade 
with a petiole-like base which is articulated with the sheath. TRIBE XIII. BAMBUSEAE. 
TRIBE I. MAYDEAE. 
Fertile spikelets imbedded in the internodes of the thick rachis. 1. TRIPSACUM. 
4 
