Dictionary.net

• tall annual marsh elder common in moist rich soil is central North America that can cause contact dermatitis; produces much pollen that is a major cause of hay fever

2006 - WordNet 3.0
By Princeton University

• tall annual marsh elder common in moist rich soil is central North America that can cause contact dermatitis; produces much pollen that is a major cause of hay fever

2011 - English Dictionary Database
By DataStellar Co., Ltd