Botanical description: Ambrosia artemisiifolia produces copious, wind-dispersed pollen in late summer causing severe hay fever in those susceptible. Recent studies show a strong correlation between climate change and the extension of ragweed season with hotter, dryer summers and delays in the first autumnal frost leading to a two to four week longer period of pollen release. Ambrosia is as likely to be found in the rich soils of agricultural fields as it is growing in dry, urban soils and places that receive regular applications of road salt. Ragweed germinates in the spring, favoring cooler temperatures than other common weeds, and can be spotted quite early. Mature plants can grow to a height of three to five feet with a stiff branching habit. It is a strong competitor for natural resources and releases allelopathic compounds into the soil that further decrease the vigor of neighboring plants. While simply obnoxious to humans, Ambrosia artemisiifolia is an integral part of the wildlife food web in North America, constituting a significant part of the diet of birds, bees, caterpillars, grasshoppers and provide small mammals with winter forage. The competitive growth of the plant has been harnessed in phytoremediation efforts to remove lead from soil.