174 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
Manual. In such cases the name used in the Manual follows in 
parentheses. For the convenience of those who use Britton and 
Brown's Illustrated Flora, the name used in the second (1913) edition 
of that work is also given in parentheses wherever it differs (except 
in spelling) from that used in this list. If the generic name used by 
Britton and Brown differs from that here used hut the specific names 
are the same (except for changes of gender), the generic name only is 
given. The Illustrated Flora, as is well known, does not recognize 
geographical varieties to the extent of naming them. It will be impos- 
sible therefore, for those who use the Illustrated Flora to discriminate 
between the species and the many varieties (over two hundred) recog- 
nized in this list. 
A great number of our native plants are not sufficiently known by 
the people to have received a genuine popular name. Only striking 
plants, like the Cat-tail, Sweet Flag, and Butterfly-weed, have names 
that are actually current. Others belong to a group which is recog- 
nized, like Cotton Grass, but species within the group are not dis- 
tinguished. Many vernacular names are given in the botanies, that 
are never used by the people, such as Dock-leaved Persicaria {Poly- 
gonum Jaixiihi folium). In the following list all names known to be in 
current use are given, and others have been copied from the Manual. 
The habitats given are those observed in the County. 
The use of the expressions valley and plateau demands a word of 
explanation. The term 'calley is used to designate the trough formed 
by the Hoosic and Housatonic Rivers and their main tributaries. It 
contains the principal limestone and moraine deposits, and its slopes 
include wooded hillsides with well-drained leaf mould. The term 
"plateau is used to designate the broad upland bounding the valley on 
the east. It is characterized by an absence of limestone and by cool 
rocky woods, ill-drained hillsides and moist fields {vid. Introduction, 
p. 182). 
For convenience, the term Greylock is used to include the whole 
mountain-mass that culminates in Mt. Greylock of the topographic 
sheet, and The Dome for the mountain-mass that culminates in Mt. 
Everett of the topographic sheets. . 
To indicate the comparative frequency of the plants listed the fol- 
lowing terms have been used, namely, "common," "frequent," " occa- 
sional," and "rare." These terms must be interpreted in connection 
