308 FOUNDATIONS OF BOTANY 
be, of a hundred other kinds — the seed-plants — not all in 
bloom at any one season, but coming along in succession 
from earliest spring until the approach of winter. The 
entire set of plants which naturally occupies a given area 
of land under somewhat uniform conditions is called a 
plant socrety. , 
379. Similar Societies due to Similar Conditions. — As 
soon as the young botanist begins to collect plants in a set 
of localities new to him, he discovers that his old acquaint- 
ances are still to be found grouped as he has been accus- « 
tomed to see them. The rich black loam of a wooded 
bank a hundred miles away from his familiar collecting 
ground will show the same assemblage of slippery elms 
and lindens, red buds, bladdernuts, and wahoos, hepaticas, 
bloodroots, Dutchman’s breeches, trilliums, pepper root, and 
wild ginger, with a multitude of later-blooming herba- 
ceous plants, that he has learned to know so well. The 
muddy borders of ponds from Maine to Minnesota and 
beyond are fringed with the same kinds of bur-reeds and 
sedges, set with water-plantain, and decorated with the 
soft white blossoms of the arrowhead. The sand dunes 
along the northern Atlantic coast and those that border 
Lake Michigan are clothed with a sparse vegetation which 
in both cases includes the little beach plum, such coarse 
grasses as that shown in Plate I, and the straggling sea 
rocket. Barnyards and waste grounds about farm build- 
ings from Massachusetts to Missouri contain such weeds 
as the dog fennel, the low mallow (“cheeses”), mother- 
wort, catnip, and some smartweeds. . 
A little study of such cases soon leads one to the con- 
clusion that these plant societies and multitudes of others 
