Cottonwoods are large, fast growing native trees found in most US states.

English Plantain is found in disturbed areas such as vacant lots, cracked pavement, grassy paths and along roadsides.

Alternaria is one of the most important allergenic molds.

This allergen is a composite of many members of the fungal family Fusarium.

Giant Ragweed is so named because it is the largest of all the Ragweed plants. It can grow as tall as 15 feet tall, and is found in every US state except for Alaska.

Hickory is prized for its lumber – extremely strong, yet flexible, it has many commercial uses.

House dust mites are one of the most significant indoor allergens in the human environment.

Johnson grass is found in all the lower US states with the exception of Maine.

Kochia is native to southern and eastern Russia, Europe and Asia. It is now naturalized across the northern half of the United States and spreading south-westwards.