Figure 4 - Cumulative number of invasive alien plant species introduced into Canada from 1600 to 2005, for which dates of introduction can be estimated

This figure shows the cumulative number of these species recorded over time, which shows roughly three phases:

1. 1600 to 1800: A period of relatively slow accumulation of new invasive alien species. (Approximately 50 invasive alien plant species introduced into Canada.)
2. 1800 to 1900: A period of more rapid accumulation, because of the faster pace of trade, immigration, and colonization, as well as increased study of the North American flora, which boosted awareness and recording of new species. (Approximately 160 invasive alien plant species were introduced into Canada, bringing the cumulative total to approximately 200.
3. 1900 onward: A period of slower, linear accumulation. (Approximately 283 species.)