These are the field guides we found useful in our travels through the wilds and not-so-wilds of the Boston Area:

Newcomb, Lawrence. Newcomb's Wildflower Guide: An Ingenious New Key System for Quick, Positive Field Identification of the Wildflowers, Flowering Shrubs and Vines of Northeastern and North-central North America. Little, Brown and Company, Boston: 1977.

Peterson, Roger Tory and McKenny, Margaret. A Field Guide to Wildflowers: Northeastern and North-central North America. Hougton Mifflin Company, Boston: 1968

Petrides, George A. A Field Guide to Eastern Trees: Eastern United States and Canada, Including the Midwest. Houghton Mifflin Company, Boston: 1988.

Uva, Richard H., Neal, Joseph C., and DiTomaso, Joseph M. Weeds of the Northeast. Comstock Publishing Associates, Ithaca: 1997.

(The links provide are to for ease of use, but the authors most whole-heartedly endorse patronizing locally owned book shops to fulfill your field guide procurement needs.)