Pumpkin Ash
Fraxinus profunda

Location in Ontario

Pumpkin Ash is a Carolinian Tree that grows in small pockets along Lake Erie. It was not identified in Ontario until the early 1990s. Pumpkin Ash prefers a swampy habitat.


Pumpkin Ash, Norfolk County
 
Genus Fraxinus
Ash trees have opposite compound leaves. Ash can be monoecious or  dioecious depending on the species. Seeds are contained in a single winged samara (a seed in a papery tissue). Ash wood is valued for its strength and hardness. Black, Red and White Ash grow in Ontario, as well as two Carolinian species, Pumpkin Ash and Blue Ash. Unfortunately, the Emerald Ash Borer has killed millions of Ash trees (see the Tree Diseases page). Black Ash has been the most susceptible to the insect, while Blue Ash shows some immunity.

TREE FACT: Ash and Hickory are similar with compound leaves, but Ash leaves are opposite while Hickory leaves are alternate.

TREE FACT:  A spring rhyme, referring to which leaves appear first;
Oak before Ash, you get a splash.
Ash before Oak, you get a soak.

In the Landscape
Pumpkin Ash is a large tree that grows to 30 metres and lives to 100 years. Everything about Pumpkin Ash is large; its size, leaves and fruit, which make it an interesting lawn specimen. However, it does like wet conditions and it is at risk to Emerald Ash Borer.

TREE FACT: In some very wet locations, the base of the tree is swollen like a "pumpkin" leading to its name "Pumpkin" Ash.


Pumpkin Ash, University of Guelph Arboretum

Leaves
Pumpkin Ash has opposite compound leaves which are large, up to 25 centimetres long! There are 5-9 leaflets, which are densely hairy beneath.  Leaves turn yellow to gold in the fall.
Bark
The bark is gray with thin ridges forming a weak diamond pattern, not as strong as White Ash.
Flowers
Pumpkin Ash is dioecious with male and female flowers on different trees. Flowers develop before the leaves in early spring and are wind pollinated.
Fruit
The samaras of Pumpkin Ash are much larger than any other Ash. Seeds form in summer, and fall off in autumn, with some persisting into winter. Seed production occurs after only 10 years of growth, but is variable, and seeds are never abundant.

Wood
Ash wood is hard and heavy. Pumpkin Ash is not commonly used in Canada due to its rareness.
Specific Gravity:
0.52
Janka Hardness: 990 lb
Wood Comparison Chart

Genetics
Pumpkin Ash is always hexaploid with 138 chromosomes; accounting for its large leaves and seeds. There is some thought that it may be a cross between a tetraploid White Ash and a diploid Red Ash, although Pumpkin Ash does reproduce readily on its own.


Pumpkin Ash, University of Guelph Arboretum

Link to United States Forest Service Silvics Manual: Pumpkin Ash

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