THE GRASS TRIBE 321 



75. C. riparia (Greater Pond-Sedge). Taller and stouter than 

 the preceding, with broader leaves, longer female spikelets on 

 longer stalks, and with more distinctly beaked fruits. Wet places \ 

 rather common. Fl. May. Perennial. 



Natural Order XCVII 

 GRAMINE^E. The Grass Tribe 



Herbs usually easily distinguished from the Sedges by having 

 their stems hollow except at the nodes, often round or somewhat 

 compressed, not angular, and the sheaths of the leaves are split 

 down on the side opposite to the blade ; flowers usually enclosed 

 in 2 or more bracts (glumes) instead of 1. The leaves are narrow, 

 parallel-veined and entire, clasping the stem with long sheaths, and 

 bear at the point where the blade joins the sheath a membranous 

 appendage called a ligule ; flowers 1 or more, in spikelets which are 

 arranged in terminal spikes, heads, panicles or racemes ; the main 

 axis of the spike or other inflorescence is often termed the rachis ; 

 each spikelet consists of a slender short axis (rachilla), usually bearing 

 3 or more chaff-like bracts or glumes ; the 2 lowest glumes (often 

 called the outer or empty glumes) are usually empty ; the next glume- 

 is known as the flowering glume, and this usually encloses another, the 

 pale, which is often smaller and thinner ; inside the pale, between it 

 and the flowering glume, may be present 2 minute scales (lodicules), 

 which are supposed to represent the perianth, 3 (rarely 2 or 6) 

 stamens, and a i-celled, i-ovuled ovary which usually bears 2 more 

 or less feathery styles or stigmas ; fruit i-seeded, seed-like ; it is 

 free or adheres to the persistent pale, and is sometimes enclosed 

 in the other glumes as well. The glumes vary considerably in 

 shape and size ; they may be obtuse or pointed, or may bear at 

 their tips, on their back or at their base, a needle-like appendage 

 (awn). The number of flowers in the spikelet, the arrangement of 

 the spikelets, and the shape of the glumes mainly furnish the 

 characters by which the genera of this difficult family are distin- 

 guished. 



The Gramineae includes about 330 genera and upwards of 3500 

 species. The fifth Order amongst flowering plants in number of 

 species, it is easily first in economic importance. Included in it 

 are the cereals and fodders which provide the staple foods of man 

 and beast. The wheat (Triticum sativum), barley (Hordeum vulgare), 

 oat (Avena sativa), rye (Secale cereale), rice (dry 'za sativa), maize 

 (Zea Mays) are a few of the grain-producing Gramineae which are 

 familiar to all. 



Though all the British species are herbs, many of the tribe 

 Bambuseae, mostly natives of tropical and subtropical regions, and 



