Alder Trees are trees in the genus Alnus of the birch family, which contains about 35 species. Birch trees and hornbeam trees are also members of the birch family. Alder Court in northern Woodland is named for our local alder trees.
Alder trees are a major cause of hay fever. They bloom from about September through November, so if you suffer from hay fever during those months, alder trees could be the culprits.
Native to Woodland
White Alder (Alnus rhombifolia) is a deciduous tree native to Woodland and to all of Yolo County except for the rain shadows just east of the Yolo County foothills and the Capay Hills. It usually grows 50 to 80 feet tall and is very fast-growing at least until reaching 20 feet tall. It prefers full sun or partial shade. It has high water needs and usually grows in wetlands. Male and female flowers are borne on the same tree, with female flowers closer to the branch tips. White Alder is ranked 9 out of 10 on the Ogren Plant Allergy Scale, indicating that it tends to cause severe hay fever. It is planted at Charles Brooks Community Swim Center and William Crawford, Sr., Park.
Non-Native
Italian Alder (Alnus cordata) is a deciduous tree from Europe. It can grow to about 80 feet tall and has lower water needs than most other alder species. Male and female flowers are borne on the same tree, with female flowers closer to the branch tips. Italian Alder is ranked 9 out of 10 on the Ogren Plant Allergy Scale, indicating that it tends to cause severe hay fever. It is planted as a street tree on 4th Street, Depot Street, and Hays Street.
