Black Hawthorn

Black hawthorn (Crataegus douglasii, Rosaceae) is a native deciduous tree widespread across western North America, reaching 15 to 30 feet tall. White flowers (13 to 15 millimeters, with 5 styles on long slender stalks) appear in broad clusters from May to June. Fruit is distinctive: ovoid, reddish-purple to black, glossy, 8 to 10 millimeters, with sweet, succulent edible pulp. The species forms thickets via suckering.

Black hawthorn grows in sun to part shade on moist soils (pH 4.8 to 7.5) with high water needs, hardy in Zones 2a to 8b. It tolerates drought, erosion, and urban conditions. Disease and pest pressure matches the genus: 7 disease and 14 pest associations documented. No cultivars are in the trade. The species has a long history as an indigenous food source.

Black hawthorn is a native that loves exactly the conditions most plants hate in the Puget Sound lowlands: saturated soils, poor drainage, and seasonal flooding. It naturally colonizes riparian zones and wet meadows. The flowers in April-May are pollinated by midges and smell like decaying fish, which is worth knowing before you plant one near a patio. The black fruit in August-September is edible and excellent wildlife food. Seven diseases are documented, with fire blight and scab the most significant, but both are less severe here than on domestic apple and pear. Fourteen pests include tent caterpillar, which can defoliate the tree but rarely kills it. For wet, poorly drained sites where other trees fail, black hawthorn is a genuine native solution. It forms thickets via root suckering, so give it room or manage the suckers.

— Chris Welch, ISA Certified Arborist