Any green plant grows where it is not wanted!
• Algae: a serious problem in aquatic ecosystem
• Gymnosperms: are naked seed plants, can be a problem in some forest system
• Angiosperms: are flowering plants, may be annuals, biennials or perennials.
• Many important weeds are in the monocotyledon fam. and the rest are in the dicotyledon fam.
• Economic impacts: yield loss
• Environmental impacts: can be alternate hosts for all other types of pests, can clog aquatic ecosystems
• Health and safety impacts: poisonous, allergenic, fire hazard, a hazard for drivers