Crataegus douglasii (Black Hawthorn)
|Also known as:
|part shade, sun; rocky river banks and shores, rock outcrops, brushy slopes, thickets, floodplains
|3 to 25 feet
|Wetland Indicator Status:
|MN county distribution (click map to enlarge):
|National distribution (click map to enlarge):
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Flat-topped, branching cluster of 5 to 25 flowers at tips of branch twigs, emerging after the leaves in late spring. Flowers are about ½ inch across with 5 round white petals. In the center are 5 to 10 stamens; stamen tips (anthers) are pale pink to nearly white.
The 5 sepals around the base of the flower are narrowly triangular, smooth along the edges or with a few stalked or unstalked glands especially near the tip. Sepals, flower stalks and the cup-shaped hypanthium below the sepals are all hairless.
Leaves and stems:
Leaves are alternate, 1½ to 3 inches long, up to 1½ inches wide, broadly elliptic to inversely egg-shaped or sometimes angular, widest at or above the middle, toothed along the edges often with a few shallow lobes, blunt to pointed at the tip, somewhat rounded to wedge-shaped at the base. The upper surface is mostly hairless except for a few hairs along veins, the lower hairless except for tufts of long hairs in major vein axils. The stalk is hairless or with sparse hairs on the upper surface and often has a few glands on the edges.
Young twigs are hairless, brown to reddish, turning gray the 3rd year and developing straight to slightly curved thorns not much more than 1 inch long. Thorns are usually abundant and are shiny maroon when young.
Mature bark is thin, gray to gray-brown and splits into narrow plates. Stems are multiple from the base and may reach 10 inches in diameter on larger stems. Compound thorns are absent, branches are erect to ascending. Plants are not colony-forming or root-suckering.
Black Hawthorn is one of the least common Hawthorns in Minnesota; its main range is centered in the Pacific Northwest, with disjunct populations around the northern Great Lakes. Its Minnesota populations are found almost exclusively within a few miles of Lake Superior's north shore in Cook and Lake counties, most often on rocky or gravelly river and stream banks and rock outcrops, less often in forest openings and brushy meadows. According to the DNR, it was originally listed as a Threatened species in 1996 when only a few locations were known, but subsequent biological surveys found it was more abundant than previously thought so it was downgraded to Special Concern in 2013.
Black Hawthorn is one of the more easily recognized Crataegus species in Minnesota from the combination of: multi-stemmed shrub (may be tree-like) lacking compound thorns; erect to ascending branches with straight to slightly curved thorns only about 1 inch long; leaves mostly hairless on the underside except in vein axils, few if any hairs or glands on leaf stalks; flowers with 5 to 10 stamens with pale pink to whitish anthers; sepals, hypanthium and flower stalks all hairless. Fruit is more oval-elliptic than globular, matures to purplish-black and is the source for the common name Black Hawthorn.
While some other Hawthorn shrubs have hairless (or nearly so) leaves, most will have a hairy flower stalk and hypanthium, red fruit at maturity, more than 10 stamens, darker pink anthers, and/or branch thorns well over 1 inch long. Location is another indicator, with Black Hawthorn restricted to the North Shore and others present outside of Cook and Lake counties.
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Photos by K. Chayka taken in Cook County. Photos by Peter M. Dziuk taken in Cook and Lake counties.
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