Blue ash, <em>Fraxinus quadrangulata</em>, Oleaceae

Blue ash, <em>Fraxinus quadrangulata</em>, Oleaceae
Blue ash, Fraxinus quadrangulata, at Elmwood Stock Farm

Blue ash, Fraxinus quadrangulata, Oleaceae

Blue ash gets its name from the blue dye obtained from the inner bark.  Ash is among the most ancient of words, from proto-Indo-European “os-” leading to Old English “aesc” referring both to ash trees and spears made from the wood of ash.

The botanical name, Fraxinus quadrangulata,  is from Latin “four-angled ash” referring to the squarish twigs.

Range: Blue ash is an uncommon midwestern species nearly always found on limestone; most abundant in the Bluegrass and Nashville Basin.

Habitat:  Typically an open-grown tree of limestone uplands, in pure stands or mixed with other Venerable Tree species. Moderately intolerant of shade, but seedlings can persist under a canopy and grow if released.

Life History: Blue ash is a long-lived slow-growing tree. Seed production is high, but germination rates are very low, typically less than 7%.  Reproduction appears to be difficult for this species in current habitats.  Seedlings and saplings can be found in bluffs of the Kentucky River, but are very uncommon on Bluegrass uplands.

Form:  Short, stout trunk with rough, irregular crown.  Large trees often with ‘stag-head’ dead tops.

Uses:  Formerly a prized species for flooring, with darker wood than white ash.

Largest known blue ash:   66″ diameter, 82′ height, 72.5″ crown spread.  Jefferson County, KY

Largest Bluegrass blue ash: 66″ diameter, 82′ height, 72.5″ crown spread.  Jefferson County, KY

Oldest known blue ash: 249 years, Cynthiana KY.

Hybrids with other ash species are not known to occur.

Map of blue ash range

Blue ash range and importance value

Fraxinus quadrangulata-4925

Blue ash leaves and samaras (fruit)

Blue ash mature stem

Blue ash mature stem

Blue ash typical form

Blue ash typical form

blue ash tree

Blue ash, typical form