

Shee FLOWERING PLANTS 
swamp has more or less stagnant, or at any rate slowly flow- 
ing, water. The vegetation of a moist meadow approaches 
Hydrophytes in character, and includes many plants which are 
social in habit, as grasses. 
The following are the chief types of vegetation in meadows : 
(i.) Grasses, some of which are especially cultivated for hay, 
whilst others form turf. The importance of grasses in a 
meadow can hardly be overrated ; they break up stiff soils by 
their long roots, or they may help to keep the surface soil from 
being washed down by heavy rains; they modify the effects of 
radiation and evaporation. 
(ii.) Herbaceous plants. These are almost always perennials. 
(Cathartic flax, Linwm catharticum, is almost the only annual.) 
They often have creeping rhizomes; the leaves are thin, flat, 
and broad, admitting of regular transpiration. The wealth of 
flowering is striking, and accounts for the abundance of insect 
life, and that, in its turn, reacts on the vegetation ; for by 
bringing about cross-pollination insects tend to insure the pro- 
pagation of plants. In meadows cultivated for hay the vege- 
tation is naturally affected by mowing, which prevents the 
ripening of seeds. Cornfields have not been discussed, because 
the conditions are artificial, owing to the planting of seed by. 
man. 
Aquatic This includes two well-marked groups of plants : 
Vegetation. (1) Those living almost entirely under water, in 
some cases even being pollinated under water—e.g., Hornwort, 
Milfoil, Grass-wrack (Zostera), Elodea, Water-soldier, ete. 
(2) Those which are partly submerged and partly out of the 
water—c.g., Yellow Water-lily, Frogbit, Pondweed, Water- 
plantain, etc. This is a far larger group than the preceding. 
Hornwort (Ceratophyllum) and Milfoil (Myriophyllum) have 
floating stems and fine linear leaves which are in whorls. 
Hornwort is adapted for pollination under water, whilst Water 
Milfoil bears its flowers on a spike which protrudes out of the 
water. When Whorled Milfoil is growing in deep, clear 
waters it appears to be pollinated under water ; but if grow- 
ing in shallow, muddy ditches, the flowers may form a spike, 
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