Trees bear both male and female flowers in late spring, but must be cross pollinated for nut production. Nuts are born in a spiny involucre or bur which opens to release the nuts in late fall. Only American trees served as an important source of lumber, due to length of their unbranched trunks. All species have been used as a source of tannin for the leather-tanning industry. All of the species can be crossed, and hybrids have been selected primarily as orchard cultivars.
Lesions expand, coalesce, and girdle the root.
Trees are killed when the root collar is girdled, or when most of the roots are killed. Breeding with resistant Asian species has produced new cultivars, and careful sanitation and site selection allow European chestnuts to still be grown. Ink disease probably accounted for the recession of chestnut from large areas in the Gulf and Atlantic states in the United States, and inland to the foothills and mountains of Mississippi, Alabama, Georgia, Tennessee, Maryland, Virginia, and the Carolinas. The fungus is assumed to have entered the United States in the mid-1800's. The second disaster for American and European chestnuts was also a fungus disease.