Spring to Fall
All species are wind-pollinated and usually produce large amounts of pollen. These plants are from moderately to significantly allergenic.
The composites are members of a large aster family (Asteraceae or Compositae). The composites have flower heads that resemble an individual flower, but the head is actually made up of numerous individual small flowers. These are the “other composites” group that includes pollens not otherwise distinguishable between each other. This group excludes all species in Artemisia or Ambrosia genus. These plants usually pollinate during the summer months.
Pollen grains are oblate-spheroidal to prolate-spheroidal; the amb triangular, 3-4 lobate and 3-4 colporate. The colpi are short or long and the ora vary within species. The sexine is thick and has long or short spines (spinules).
The pollen grains vary from 15-48 x 16-40 micrometers.
The shaded areas on the map indicates where the genus has been observed in the United States.
Enter a full or partial species name to find more information on one of over 1,200 potentially allergenic plants.
For example, you can find chenopods searching on "cheno"