xiv INTRODUCTION 
|. In idc the following special groupings of provinces are often 
found eonven : 
“Coastal ‘Plain and adj. provinces.” Plants thus annotated appear 
to reach their maximum development on the Coastal Plain, but also occur 
northward and westward in the Piedmont, Appalachian Valley, Appa- 
lachian Plateau, and other provinces which border the Coastal Plain. 
“Various provinces, in Coastal Plain only N.” These plants are not 
known to grow in the Coastal Plain within our limits, although they may 
be abundant in or even typical of that province further northward, as in 
Va., Md., or N. J. 
“Blue Ridge and more N Provinces.” In this manner are designated 
plants which reach their greatest development in regions north (and north- 
west) of our limits, or in some cases in the Rocky Mountains. 
s the states of Florida, Mississippi, and Louisiana lie essentially 
within the Coastal Plain, plants limited to them have not required spe- 
cial mention of province. Moreover, plants occurring “in salt-marshes 
along the coast” or “on sand-dunes,” are so obviously limited to the Coastal 
Plain that statement of it has been omitted. It is of course realized that 
the Coastal Plain is not an ecological unit, being divisible into a consider- 
able number of areas with different soils and other features; however, in a 
work of the scope of the present volume it is impracticable to go into 
details in this respect, which must be left for the writers of local floras. 
. While every effort has been made to have these province-assignments 
ue the data in the literature are often inadequate to decide the exact 
of g spe icd and errors which users of this work may discover 
will "s aa eee rece 
Range.—Instead of eallowiue the usual plan of beginning range state- 
ments at the northeast, we begin at the southeasternmost state within our 
limits at which the plant is known to occur. When the starting-point lies 
toward the eastern coast, the final state named is that lying furthest north- 
east, as “Ga. to La., Minn, and Me.” When, however, the start is made 
far inland, the last PN given is the southernmost in which the plant ap- 
proaches the coast, as “Tenn. to Mo., Mich., N. Y., and Va.” The pri- 
mary reason for this method is that his manual covers southern plants, 
= and users are naturally most interested in the places where the plant 
occurs in the south, hence it is convenient to have the southern limits 
come first. There is, however, also a scientific significance to the plan, in 
that the last great plant migration on this continent, resulting from the 
climatic change connected with the retreat of the ice-sheets of the final 
stage of the Glacial Period, consisted in a movement of plants from south 
to north, of which the range as stated may give a rough picture. 
J. K. S. 
