16 STRUCTURE 
inflorescence) breaks up at the joints or nodes, and each internode 
as it breaks off carries away with it a spikelet enclosing the fruit. 
In those grasses which have many-flowered spikelets, like Poa and 
Bromus, the rachilla (axis of the spikelet) is jointed, and its inter- 
nodes break away separately, each with a fruiting glume attached 
(fig. 34). One-flowered spikelets often drop off the pedicel entire, 
eg. Alopecurus and Panicum. Very frequently the grain adheres 
permanently to the palea, and sometimes also to the flowering 
glume; but whether adherent or free, it is nearly always enclosed 
in both, and as the fruiting glume retains the distinctive characters 
of the flowering glume, the fruits of the different species can be 
discriminated from each other by means of these spurious cover- 
ings. The fruit of the Bromes, for example, is distinguished by 
the apical notch and the straight subterminal awn of the fruiting 
glume (fig. 32) ; that of the Oat-grasses by the long geniculate and 
twisted dorsal awn (fig. 20) ; that of Amthoxanthum is enclosed in 
the second pair of empty glumes (fig. 13). . When the entire spikelet 
falls off, as in Panzcum, all the glumes persist around the fruit. In 
some grasses the fruiting glume has a tuft of hairs at the base, as 
in Calamagrostis, Ammophila, and Deschampsia. In Poa these 
hairs are cobwebby (arachnoid). Sometimes, eg. Phalaris, 
Panicum, and Milium, the fruiting glume becomes hard and 
polished. Many other examples could be cited, and the student 
who acquires a thorough knowledge of the distinctive characters 
of the flowering glume, will have no difficulty in discriminating the 
so-called seeds of the different species. 
Enveloped in one or more light chaffy glumes, the fruit is nicely 
equipped for wind-dispersal ; for evidence of the colonizing powers 
of our meadow and pasture grasses, we have only to examine a 
piece of naked or mossy ground in autumn or spring, and we shall 
find hundreds of seedling grasses. Long, bent and twisted awns, 
like those of Sta and Avena, are able to bury the fruit. The 
former are not native grasses, but the long feathery awns of S. 
pennata may often be seen in bouquets of dried grasses. Glumes 
awned in this manner are usually barbed at the base with stiff 
hairs, and the curvature and hygrometric movement of the awn, 
after the fruit has fallen to the ground, gives a screwing motion to 
the fruit, which thus bores its way by degrees into the soil or works 
into crevices. Sta spartea, a North-American grass, misuses 
the power that Nature has endowed it with; its long awns fix 
themselves in the wool of sheep and penetrate the flesh. Wind is 
the universal disseminator of grass-fruits, but those with scabrid 
glumes or awns often adhere to the fur and feathers of animals 
and birds, and are thus transported to fresh localities. Migratory 
birds carry the grains, embedded in mud on their feet, over the 
sea to neighbouring islands and to other continents. Man himself 
undesignedly acts as a disseminator, by sowing weed-grasses along 
with cereal and other crops in a tilled soil, where they flourish and 
cannot be extirpated. Hence it is that certain agrarian species of 
grasses are found in every part of the civilized world. 
