Alder

Alder, common name for a group of shrubs and trees native to cold and temperate climates. Because the alder's wood resists decay underwater, it is used for bridge pilings. Dye was formerly obtained from the bark of many species. The black alder is a native of Europe. It usually grows to about 15 m (about 50 ft). Among the varieties used for ornamental planting are the golden alder, with bright golden-yellow leaves, and the cut-leaved alder, with narrow, deeply incised leaves. The gray, or Eurasian white, alder has acute leaves, downy underneath, and grows to a height of about 24 m (about 80 ft).

Scientific classification: Alders belong to the family Betulaceae. The black alder is classified as Alnus glutinosa and the gray alder as Alnus incana.