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Fraxinus quadrangulata (Blue ash)
Makin, Julie

Fraxinus quadrangulata

Fraxinus quadrangulata Michx.

Blue Ash

Oleaceae (Olive Family)


USDA Symbol: frqu

USDA Native Status: L48 (N), CAN (N)

Blue ash grows 50-70 ft. in height and develops a slender, straight, slightly tapered trunk which supports a narrow, rounded, crown of spreading branches. Young twigs have four winged, corky ridges running lengthwise along the bark. The deciduous foliage is similar to other ashes, turning yellow in fall. The bark is different than other ashes, having a scaly appearance.

The name, quadrangulata, means 4-angled and refers to the 4 corky ridges on the twigs. This characteristic distinguishes blue ash from all other ashes. Another unique feature is the sticky sap from the inner bark, which turns blue when exposed to air


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Plant Characteristics

Duration: Perennial
Habit: Tree
Autumn Foliage: yes
Fruit: Green
Size Class: 72-100 ft.

Bloom Information

Bloom Color: Green , Purple , Brown
Bloom Time: Apr


USA: AL , AR , GA , IA , IL , IN , KS , KY , MI , MN , MO , MS , OH , OK , TN , VA , WI , WV
Canada: ON
Native Distribution: Extreme s. Ont., MI & WI, s. to GA, n. AR & extreme s.e. KS
Native Habitat: Lowland wet to upland dry, open woods

Growing Conditions

Light Requirement: Sun , Part Shade
Soil Moisture: Moist , Wet
Soil pH: Circumneutral (pH 6.8-7.2)
Soil Description: Variable.
Conditions Comments: Blue ash is fast-growing yet long-lived. It is tolerant of various climates and soils, and is unique among the ashes for its tolerance of drought and alkalinity. The inner bark of the tree reveals blue coloring when mixed with water, giving reason for the common name. Susceptible, like many ashes, to a wide variety of disease and insect pests; these usually are not a problem to vigorously growing trees.


Description: Seeds may be sown outdoors after collection or stored and stratified then sown in spring.
Seed Treatment: Stratify in moist sand or perlite for 30-60 days at 41 degrees.
Commercially Avail: yes

Additional resources

USDA: Find Fraxinus quadrangulata in USDA Plants
FNA: Find Fraxinus quadrangulata in the Flora of North America (if available)
Google: Search Google for Fraxinus quadrangulata


Record Modified: 2012-07-31
Research By: TWC Staff

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