PLANT SOCIETIES 247 



to the almost xerophytic barrenness of dusty lanes and gul- 

 lied hillsides. The forms and conditions they present are 

 so diversified that it will be impossible even to touch upon 

 them all in a work like this, but they may be summed up 

 under the two principal heads of open ground and wood- 

 land growth. Under the first are included all cultivated 

 grounds ; fields, lawns, meadows, pastures, and roadsides, 

 with their characteristic weeds, flowers, and grasses. Under 

 the second, all woods and copses with thp shrubs and herbs 

 that form their undergrowth. 



354. Halophytes include plants growing by the seashore 

 and the vegetation around salt springs and lakes and that of 

 alkali deserts. Seaweeds are in a sense halophytes, since 

 they live in salt water, but as they are true aquatic plants 

 and exhibit many of the peculiarities of hydrophytes in 

 their mechanical structure, they are classed with them. 

 The name halophyte applies more particularly to land 

 plants that have adapted themselves to the presence of 

 certain minerals, popularly known as salts, in the soil or in 

 the atmospheric vapor. If you have ever spent any time 

 at the seashore, you can not fail to have been struck with 

 the thick and fleshy habit exhibited by many of the plants 

 growing there, such as the samphire, sea purslane (Sesn- 

 viuni), and sea rocket (Cakile). A form of goldenrod 

 found by the seashore has thick, fleshy leaves, and is as 

 hard to dry as some of the fleshy xerophytes. 



Another characteristic of desert plants that is common 

 also to seaside vegetation, is the frequent occurrence of a 

 thick, hard epidermis, as in the sea lavender and saw 

 grass. The live oaks, trees that love the salt air and 

 never flourish well beyond reach of the sea breezes, have 

 small, thick, hard leaves, very like those of the stunted 

 oaks that grow on the dry hills of Cahfornia. The 

 presence of spines and hairs, it will be observed, is also 

 very common ; e.g. the salsola, the sea ox-eye, and the 

 low primrose {CEnothera humifusa). In other cases the 

 leaf blades are so strongly involute or re volute (Sec. 60) 



