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This is the most common and weedy goldenrod in Illinois. The flowers are especially attractive to many species of wasps and flies, which play an important role in controlling insect pests, or breaking down organic matter in the detritus cycle. The species Solidago altissima (Tall Goldenrod) is considered a variety of Canada Goldenrod by some authorities, while others (e.g., Mohlenbrock, 2002) treat it as a separate species. According to the latter authority, Tall Goldenrod has longer phyllaries (floral bracts) at the base of its flowerheads (exceeding 3 mm. in length), while Canada Goldenrod has shorter phyllaries (3 mm. or less). It has been reported that the foliage of Canada Goldenrod contains a volatile oil that chemically resembles the oil from pine needles. There is also some experimental evidence that this species inhibits the growth of maple seedlings, and probably other plants as well, by exuding phytotoxic chemicals through its roots. Return