Boone County Arboretum
9190 Camp Ernst Road
Union, Kentucky 41091
Phone: (859) 384-4999
Fax: (859) 384-6888
arboretum@boonecountyky.org

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Cultural Details for Alnus glutinosa 'Imperialis'

Common Name:
Cut-leaf European Alder (Black Alder)

Growth Rate:
weak pyramidal to narrow pyramidal. Fast in youth, tends to slow down; 24-30’ per year over a 20 year period.

Average Mature Height:
40-60'

Average Mature Width:
20-40'

Flower Details:
In March before leaves. Male flowers – reddish brown 2-4" long catkins. Female flowers – purplish, egg-shaped

Fruit Details:
Nutlet, borne in persistent 0.33 to 0.66” long ovoid strobile, on 0.5-1” long peduncles matures in October-November

Fall Color:
none. Leaves fall off green or brown.

Bark Details:
Young bark is gray-green or greenish brown; brown with age.

Disease / Insect Problems or Resistance:
Powdery mildew rarely serious, cankers can be a problem, leaf rust-rarely serious, woolly alder aphid, alder flea beetle, alder lace bug, leaf miner, sawfly, and tent caterpillar

Native Habitat:
Species native to Europe, western Asia, northern Africa.

Other Features:
‘Imperialis' deeply cut, light green leaves.

Culture and Care:
Transplants readily; prune in winter or early spring; if used along waterways will seed in along the banks and eventually cover large areas; species can grow submerged in the water; a nitrogen fixing species. Zone 4-7.

This plant was blooming:
3/22/2007 - 4/5/2007

Plantings of this cultivar at Boone County Arboretum:
1014, 8481

    The information on this page may have come from one or more of the following sources:
  • Dirr, Michael. Manual of Woody Landscape Plants. Stipes Publishing. 1998.
  • Hightshoe, Gary L. Native Trees, Shrubs, and Vines for Urban and Rural America. John Wiley & Sons. 1988.
  • North Carolina Extension Plant Fact Sheets. www.ces.ncsu.edu
  • University of Connecticut Plant Database. www.hort.uconn.edu