CHAPTER III 
Classification 
THE Graminee@ as a family are readily distinguished from all 
other plants; the most {nearly related order is the Cyeracee 
(Sedges), but differing from the grasses in many characters, ¢.g. 
the three-sided stems, entire leafsheaths, absence of ligule ; flowers 
without a palea, anthers basifixed and entire at the apex, styles 
solitary with simple, not feathery, stigmas ; ovary surrounded by 
bristles or enclosed in an urceolate (bottle-shaped) bracteole or 
perigynium ; embryo at the base of the endosperm, not lateral. 
But while the grasses are such a very natural family, their classifi- 
cation into primary division, tribes, and genera is more difficult 
perhaps than that of any other order of plants. The flowers and 
fruit are of very little value for this purpose, and the characters are 
mainly drawn from the structure of the spikelets and the various 
modifications of the glumes. None of the groups can be defined 
one from another absolutely, as there are ambiguous or intermedi- 
ate forms connecting them, the result being a network of genera 
related in different ways and various degrees. We shall give, as 
plainly as possible, a short account of Bentham’s classification and 
a synopsis of the British genera, noting the exceptions as they 
occur in the different tribes. 
The grasses are divided into two great series, Pandcacee and 
Poacee, and this primary division is founded upon a combination 
of two kinds of characters: first, the articulation of the spikelet 
upon the pedicel, or the articulation of the rachilla (axis of the 
spikelet) ; secondly, the position of the imperfect flower or third 
empty glume or rudiment (when present) in relation to the bi- 
sexual flower, that is, whether situated above or below it. 
We have seen, when considering the structure of the spikelet, 
that the significance of the articulation lies in the fact that it 
determines the manner in which the fruit is liberated. If, for ex- 
ample, the spikelet is jointed upon its pedicel, when the fruit 
matures the entire spikelet will drop off. This is what takes place 
m the Panicacee ; normally, not a glume remains on the rachis or 
branches of the panicle after the fruit is dispersed. 
In the Poacee the spikelets are not (with some exceptions) 
jointed on the pedicel ; the articulation is in the rachilla, so that 
when the fruit is mature each internode of the rachilla breaks away, 
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