The Encyclopedia Americana (1920)/Beach Plants
BEACH PLANTS. Plants living normally on shores, particularly of the sea, or on the contiguous dunes and marshy strips, are usually characterized by fleshiness, leatheriness, downiness or dense hairiness. This is true of the maritime members of families otherwise quite different in appearance, and these peculiarities, resembling those of plants living in other saline and arid localities, are devices resulting from adaptation to similar desert conditions, for the beach sands become very hot and naturally receive practically no water from either sea or land, and are unable to conserve the rainwater. Thus the strand becomes a strip of desert. The succulence and unctuousness of such common plants as the seaside goldenrod (Solidago), of the saltmarsh and smooth aster (Aster), of certain huge tropical morning glories (Ipomœa), of the marsh-rosemary (Statice), of the yellow sand-verbena (Abronia) and others, are evidence of efforts on their part to store such water as may fall upon them, in the cells of their swollen tissues, and also to prevent its evaporation through the stomata. Some plants, as the Polygonella and the marsh-samphire (Salicornia), have further reduced their transpiring surface by assuming a cylindrical shape with scale-like leaves. Terete also are the bases of the leaves of the saltwort (Salsola) which are armed, against the attacks of animals wishing to forage on their juicy foliage, by stout prickles. Many of these fleshy plants also contain salts in their tissues that are strongly retentive of water; the saltwort having formerly been burned to obtain soda from its ashes. Others, like some tamarisks, exude salts that form a crust over the stomata pits in the daytime but by attracting dew and the moisture in the air and becoming liquefied furnish a certain amount of water at night.
The bearberry (Arctostaphylos), the bayberry (Myrica) and the beach plum (Prunus) exhibit the leathery and pubescent type of foliage calculated to resist drought by restraining transpiration by means of the thickened skin and hair. The pale pubescent under-surface of the latter's leaves occurs on plants living near water, and is designed to keep arising moisture from settling in and flooding the stomata.
Velvety pubescence on all surfaces attaining to the same end is present in the marshmallow (Althæa) and the clotbur (Xanthium). Many of the salt-marsh plants are decidedly hairy, serving the purpose of controlling evaporation and preserving the leaf from too much moisture.
Some of these beach-plants are useful aids in preventing the shifting of sands and dunes, the most important being the coarse grasses, marram (Ammophila) and sea-lyme (Elymus), whose tough long roots interweave through the sand, forming a mat that holds it in place. The beach thus reclaimed is gradually settled upon by sundry other sand-binding plants, as the bayberry, bearberry, abronias, beach plums, etc.; and certain trees as the tamarisk, some species of pines and cedars are also found there or may be planted. Consult Marilaun, A. Kerner von, ‘Natural History of Plants’; Scribner, F. L., ‘Sandbinding Grasses’ (reprint from Yearbook of Agriculture, 1898), and ‘Economic Grasses’ (United States Division of Agron., Bulletin 14); ‘Stock Ranges of Northwestern California’ (Bulletin 12, Bureau of Plant Industry, United States Department of Agriculture).