Oklahoma Alder, Seaside Alder 'September Sun'

'September Sun', an autumn blooming shrub, is the first cultivar selected during a trial of A. maritima subsp. oklahomensis seedlings on ...Read Morethe campus of Iowa State University, Ames. The seed was obtained from an open-pollinated A. maritima subsp. oklahomensis growing on the bank of the Blue River near Tishomingo, Oklahoma.

Mature plants are large shrubs or small trees with multiple trunks, broadly rounded, upright canopies, 7 meters tall and 5 meters wide.

Alnus maritima is monoecious and the only species of Alder native to North America that blooms late in the growing season. Yellow pendulous catkins appear from mid August to late September. The catkins are produced in clusters of two to six at tips of most branches before leaf coloration begins in the fall.

The infructescences are medium to dark brown, cone-like strobili; each is 16 to 22 mm long and 11 to 14 mm in diameter. Strobili mature 1 year after pollination and stay on the branches through at least one more season.