Information on Showy Mountain Ash Trees

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Q: I would kindly like information on the tree called Showy Mountain Ash (Sorbus decora). I was reading a little about this tree and it states that it is not susceptible to the fire blight. I was wondering if it is disease-free and long-lived. Also what is the height and width? Does this tree have flowers, and, if so, what colour and also berries that the birds like?

During the 10 years that I was horticulturist at VanDusen Botanical Garden, I took the Garden Guides on monthly educational walks. In November 2001 we took a detailed look at the Garden’s Sorbus Collection, which is centered northeast of the Great Lawn. At that time, there was a Sorbus decora, about which I still have the following notes:

Sorbus decora is native to E North America, from Saskatchewan east to Newfoundland and north to Greenland. It grows into a small tree or shrub bearing stout twigs. Its large, conical leaves have up to 15 leaflets to 7.5 cm long each. In the fall it develops large red fruits in large drooping clusters, somewhat hidden by leaves; these are popular with birds.”

One of my favorite Sorbus at VanDusen were the S. commixta in the Sino-Himalayan garden. They must have been grown from seed, as on had pumpkin-orange fruits and one had red fruits.

They formed multi-stems trees to about 15 feet high.

S. ‘Joseph Rock’ is also in the lawn collection. Its fruits are golden and glow in autumn. (Most members of the Rose Family are susceptible to fire blight, and S. decora is no exception. The presence of the disease depends in part on the weather. I never saw any sign of it on the VanDusen trees, but UBC Botanical Garden had problems with it on S. ‘Pink Pagoda’, which was a UBC introduction.)

I hope you will take a trip to VanDusen and UBC botanical gardens to visit these trees.