Betula populifolia multiple trunks branching off of an old stump. The leaves are 5-7.5 cm long by 4–6 cm wide, alternately arranged, ovate, and tapering to an elongated tip. They are dark green and glabrous above and paler below, with a coarsely serrated margin. The bark is chalky to grayish white with black triangular patches where branch meets trunk. It is most easily confused for the paper birch ("Betula papyrifera") by means of its bark; it is smooth and thin but does not readily exfoliate like paper birch does. The flowers are wind-pollinated catkins 5–8 cm long, the male catkins pendulous and
Citrus gummy bark viroid observed in longitudinal sections. Citrus gummy bark viroid The citrus gummy bark viroid (abbreviated CGBVd) is a sub-species of the hop stunt viroid, and thus is a member of the genus Hostuviroid. As the name suggests, the citrus gummy bark viroid causes problems in the bark of the sweet orange tree. Scrapping the bark exposes localized spots or a line of reddish-brown, gum-impregnated tissue around the scion circumference especially visible near the bud union. The discoloration and gumming may extend above the bud union to the main branches of the sweet orange while in severe infection dark streaks of gum-impregnated