A Canadian Rarity: the Hop Tree

Hop Tree (Ptelea trifoliata)

Hop Tree (Ptelea trifoliata)

When I was working as a naturalist on a Great Lakes cruise ship, we often visited the sand dunes on Lake Michigan near Saugatuck. While the passengers were racing around on dune buggies, I walked about admiring the local flora and fauna. One small tree which caught my eye was the Hop Tree (Ptelea trifoliatum).

Hop Tree (Ptelea trifoliata)

Hop Trees thrive on forested and open dunes along Lake Michigan.

While leading walks in Sunnybrook Park along the West Don River, I have occasionally noticed a tree with 3 leaflets on a central stock which bear a surprising resemblance to Poison Ivy Leaves.

Poison Ivy (Toxicodendron rydbergii)

Hop Tree (Ptelea trifoliata)

This is the Hop Tree. Trees in Canada (John Laird Farrar, p. 230) describes the tree as Rare in Canada; occurs in southwestern Ontario on the north shore of Lake Erie. No indication of it growing near Toronto. Michigan Flora (Voss and Reznicek, p. 863) mentions that it will grow along rivers and the edges of floodplain forests. This is a perfect description of Sunnybrook Park near the Don River.

The leaflets are nearly stalkless and the margins are nearly smooth. There is a strong citrus odor when the leaves are bruised.

Hop Tree (Ptelea trifoliata)

Here is a view of the leaf underside.

Hop Tree (Ptelea trifoliata)

The lateral buds are very small and sunken.

Hop Tree (Ptelea trifoliata)

The flowers are small and greenish-white.

Hoptree flowers (University of Guelph)

The fruits are flat and one or two seeded.

Hop tree fruit (Wikipedia)

The bark is reddish-brown and smooth when young.

Hop Tree (Ptelea trifoliata)

Hop Tree (Ptelea trifoliata)

Hop Tree (Ptelea trifoliata)

It becomes rough with age.

Hop Tree (Ptelea trifoliata)

Hop Trees grow up to about 8 meters in height and 15 centimeters in diameter.

Miles Hearn










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