434 THE ECOLOGY OF PLANTS. 



and hence for lack of oxygen the roots are unable to develop 

 to any great extent or to penetrate deeply. If mixed with 

 sand, chalk, or humus, however, the soil is much improved, 

 and many plants will survive periods of drought on such soils, 

 whereas they may perish on more porous ones. Such plants 

 as Lily of the Valley, Lesser Celandine, Wood Sanicle, Colts- 

 foot, Primrose and Cowslip, Bittersweet, Yellow Dead-nettle, 

 Garlic, Early Purple Orchid, Blue-bell, are found, in some 

 districts at least, to prefer soils containing a good deal of clay. 



410. Sand-Plants. These include (a) those plants which 

 prefer merely a sandy soil, and (6) those of the sea-coast 

 (strand-plants) which have adapted themselves to the 

 presence of salt. Many such plants grow equally well in 

 ordinary soil, but lose certain of their characteristics, and 

 probably would not survive if left open to free competition. 

 Practically all such plants have strongly xerophilous char- 

 acters; for example, reduced leaf -surf ace, thick fleshy or 

 prickly leaves and stems, stunted habit, thick cuticle, deeply 

 sunk stomata, etc. Sand-plants, pure and simple, are often 

 very prickly, thorny, or hairy, whereas hairs are usually 

 absent or few in number on strand-plants. 



The following are a few examples of sand - preferring 

 plants : Mousetail (Myosurus, Ranunculaceae), Sand Spurrey, 

 Stork's-bill (Erodium, allied to Geranium), Broom, Worm- 

 wood, G-olden-rod, Wood Sage. 



411. Strand-Plants. The plants which grow along our 

 shores, either on sand or in mud-flats (salt-marshes), are 

 sometimes called Halophytes, or saline-plants. They either 

 prefer salty soil, or grow here because their competitors are 

 more sensitive to salt and are unable to follow them. All 

 strand-plants are more or less xerophilous in character, and 

 this is also the case with regard to plants growing on salt- 

 marshes or muddy shores. Here the plant strives to reduce 

 its need of absorbing water to a minimum, so that it shall 

 not absorb too much salt. Hence the plants are fleshy or 

 leathery, the cuticle is thick, the stomata often sunken, and 

 the leaf-surface often reduced or spiny. Since high winds 

 often prevail, the flowers are usually small, and the seeds 

 are rarely winged, but there are exceptions to both these 



