A plant genus of the family ASTERACEAE known for allergenic pollen (ALLERGENS).
Rhizosphere
The immediate physical zone surrounding plant roots that include the plant roots. It is an area of intense and complex biological activity involving plants, microorganisms, other soil organisms, and the soil.
Host Specificity
The properties of a pathogen that makes it capable of infecting one or more specific hosts. The pathogen can include PARASITES as well as VIRUSES; BACTERIA; FUNGI; or PLANTS.