This section contains the definitions of many of the ecological terms used to describe the various weed species.
The ecological information compiled for each species on this Web site came from a variety of sources. Since the intent of this database is facilitation of weed management by home and market gardeners, we have not included lists of references documenting each statement. A complete reference list would include several hundred citations. Much of the information, however, came from the sources listed below. We are particularly indebted to the series "The biology of Canadian weeds", published in Canadian Journal of Plant Science and compiled in the four volumes cited below, to the series "The intriguing world of weeds" published regularly in the journal Weed Technology (see index by Mitich listed below for sources prior to 1991), to a series of experiment station bulletins on particular species published by various universities in the Northeast (see below), and to the Ecological Flora of the British Isles at the University of York. In addition to these formal sources we relied substantially on our 40+ years of personal observations, both published (see About Us > Publications) and unpublished, on these weed species.