Winter to Summer
Sweet-gum is considered to be mildly allergenic and found primarily in eastern U.S.
A native ornamental tree of the eastern U.S., Sweet-gum is valued for its foliage and scarlet autumn leaf color. The cone-shaped, aromatic deciduous tree will grow over 100 feet tall. The dark green leaves are star-shaped with 5-7 lobes and are about 4-7 inches across. Inconspicuous upright staminate (male) and pendulous pistillate (female) flowers are in separate, round greenish clusters on the same tree. Flowers appear in April and May as leaves emerge and are wind pollinated. A large number of round, prickly seed capsules are produced in late summer.
Pollen grains of sweetgum are easy to identify by their spheroidal shape and pantoporate apertures with up to 20 large circular pores. The surface patterns of the grains are reticulate.
Pollen grains vary in size from 34-43 micrometers.
The shaded areas on the map indicates where the genus has been observed in the United States.
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