Betula populifolia the female catkins erect. The fruit, maturing in autumn, is composed of many tiny winged seeds packed between the catkin bracts. The wood is medium hard and is used for high grade plywood, furniture, drum shells, spools and firewood. Like other North American birches, gray birch is highly resistant to the Bronze birch borer ("Agrilus anxius"). The leaves of the gray birch serve as food for various Lepidoptera, such as the leaf miner moth "Cameraria betulivora". Between about 1930 and 1950, many gray birch trees, along with paper birch and yellow birch ("Betula alleghaniensis"), were affected and killed by birch
Cyclocarya female catkins 25–30 cm long at maturity, bearing several small winged nuts with a circular wing 2.5–6 cm diameter right round the nut (instead of two wings at the sides as in "Pterocarya"). Cyclocarya Cyclocarya is a genus of flowering plants in the family Juglandaceae, comprising a single species Cyclocarya paliurus (qing qian liu or wheel wingnut), formerly treated in the genus "Pterocarya" as "Pterocarya paliurus". It is native to eastern and central China. It is a deciduous tree growing to 30 m tall. The foliage is similar to "Pterocarya", with pinnate leaves 20–25 cm long with five to eleven