1903] Blankinship, — Plant-formations of E. Massachusetts 127 
appears to fall into this latter class of generalized species, though the 
list of characteristic species may be largely extended. 
It is only by thus dividing the flora of a district into its component 
plant-formations and recognized habitats that any system can be intro- 
duced into the present unscientific method of quoting specific habi- 
tats and any studies attempted on specific variation based upon the 
influence of environment. 
The local plant-formations may best take their names from the 
habitats of which they are characteristic and hence in the district 
here considered we have the following : 
SYNOPSIS OF THE PLANT-FORMATIONS OF EASTERN MASSACHUSETTS. 
I. Soil humidity slight. Xeropkytes or Arid Plants. 
(Little or no forest Mi dai and hence no shade.) 
A. Soilsilicious  . : c f I, SAND-BARREN FORMATION. 
B. Soilargillaceous. : : 2. MirrToP-BARREN FORMATION. 
II. Soil humidity medium. Mesophytes or Upland Plants. 
(These uplands forested and consequently mainly shade vegetation.) 
A. Soilsilicious . i : 3 3. SAND-PLAIN FOREST FORMATION. 
B. Soil argillaceous  . 4. HILLY UPLAND-FoREST FORMATION. 
III. Soil humidity gr reat. ` Hygr ophytes or Lowland Plants. 
a. In full sunlight. 
A. Soil silicious . : . : 5. SAND-POND MARGIN FORMATION. 
B. Soilargillaceous . : , À 6. Low-MEADow FORMATION. 
C. Soil saline (Halophytes) . . : . 7. SEA-SHORE FORMATION. 
b. In the shade. 
A & B. Soilsilicious or argillaceous with abundant humus. 
8. Low-WooDLAND FORMATION. 
IV. Soil saturated. Helophytes or Swamp Plants. 
a. In full sunlight. 
A & B. Soilsilicious or argillaceous. 
with little or no Sphagnum ^ ga. SWAMP FORMATION. 
with much Sphagnum : 1 gb. Boc FORMATION. 
C. Soil saline (7/alophytes) . : » IO. SALT-MARSH FORMATION. 
b. In deep shade. 
A & B. Soilsilicious or argillaceous 11. BoGGv-WooDLAND FORMATION. 
V. Soilsubmersed. AHydrophytes or Aquatic Plants. 
(All necessarily in full sunlight.) 
a. Plants fixed. 
A. Substratum sandy : , : : 12. SAND-POND FORMATION, 
B. Substratum argillaceous : . : 13. Mup-Ponp FORMATION. 
C. Substratum saline : : 14. SEA-SHOAL FORMATION. 
à. Plants floating freely; substratum unimportant. 
A&B. In fresh water . : . r 15. FRESH-WATER FORMATION. 
C. In salt water : : : ; " . 16. PELAGIC FORMATION. 
VI. Special Adaptations. Brophytes. 
a Dependent upon human habitation 17. WASTE-LAND FORMATION. 
b. Cultivated by man for his use or admiration 
18. ECONOMIC FORMATION. 
c. Saprophytic or parasitic on other organisms 
19. FUNGOID FORMATION. 
