M
Maryum Chaudhry
Guest
- Thread Author
- #1
October is often the best month to see berries and other colourful fruits and—hungry birds notwithstanding—2026 will go down as an impressive year in the Botanical Garden for viewing many of them. Mountain ashes, European and Asian whitebeams and their close relatives are front and centre in showing off their beautiful “berries.” Botanically, they are pomes, more in common with apples and pears, than with the true berries like blueberries and grapes. The whitebeams have simple, toothed leaves, much like those of elms or apples, and often dull or darker coloured pomes, while the more familiar mountain ashes—i.e., Sorbus species—have pinnate (feather-like) leaves with narrow leaflets arranged at right angles to a central leaf stalk, and usually, small, glossy pomes.
There are several “problems” with Sorbus, not least that the common European mountain ash, S. aucuparia, is an invasive species that shows up uninvited in local woodlands, including at UBC Botanical Garden. We keep a close watch on the three dozen or so of our own mountain ashes for this reason. Thankfully, we haven’t seen spontaneous seedlings outside of our irrigated areas, and this suggests that they can’t survive beyond our fences.
Especially this year, visitors may have noticed an increase in leaf “skeletonizing” caused by the mountain ash sawfly (Pristiphora geniculata). Sawflies are small, fly-like wasp relatives, the larvae of which are yellow and brown inchworm-like caterpillars. The small, pink-fruited Sorbus macrantha opposite the Moon Gate in the David C. Lam Asian Garden is annually defoliated in summer and a good example of the voraciousness of this exotic pest. The fact that this little tree continues to rebound, however, suggests that Sorbus are not entirely at the mercy of these caterpillars. Nevertheless, there is much about the sawfly’s reproductive biology and host preferences that we do not understand. All we can do is continue to monitor which species are affected, their locations and the degree of defoliation they endure.
By some trick or unseen circumstance, a few mountain ashes in the Asian Garden remain untouched—including the spectacular red-fruited Sorbus splendens (atop a stump at Stearn and Farges Trails), the tall, elegant, white-fruited Sorbus discolor on Upper Asian Way at Ludlow Trail, and the always praise-worthy, yellow-fruited Sorbus ‘Joseph Rock’ on top of the northwestern slope above the Roseline Sturdy Amphitheatre. Happily, the whitebeams are immune to the ravages of the sawfly. I’ve written at length about whitebeams and mountain ashes (they’re an obvious choice for describing autumn fruit in the Garden), but as recently as November 2024, I described the Asian whitebeams as belonging to the genus Aria. For readers who are keeping track, they are now properly listed under the genus Micromeles. Aria is a genus whose species are restricted to Europe and western Asia, while Micromeles species are native to Southeast Asia and the Himalayas.
An example of the resilience of the Asian whitebeams can be seen in the beautiful orange-fruited Yu’s whitebeam, Micromeles yuana, near the corner of Upper Asian Way and Lam Trail near the entrance to the David C. Lam Asian Garden. But again, I’ve described this species in print many times, albeit first under Sorbus, then Aria and now, Micromeles. Micromeles alnifolia, the alder-leafed whitebeam, is another attractive Asian tree, and one I’ve not featured here. This variable species is widespread in Asia and more commonly known in commerce by its older names Sorbus alnifolia (and Korean mountain ash). This particular specimen, where Handel-Mazetti and Soulie Trails meet, is both elegant and lofty, with tiny orange-red fruits that are visible now, but soon obscured by the similarly-coloured turning leaves.
It has been some years since I wrote about the rare Micromeles karchungii (at the corner of Ludlow Trail and Lower Asian Way). This Bhutanese species produces lozenge-shaped, lemon-yellow and later, apricot-coloured pomes, and this year, they are definitely worth a look, though it has grown tall and the fruits may not be visible until leaf fall. Close by in the Wharton Glade are a couple of pome-laden blueberry whitebeams, Micromeles aronioides. Native to the mountains of southwestern China and Myanmar, this species bears small purple pomes covered in a waxy bloom, which makes them look like blueberries. Finally, rounding out the food theme are two of our green-fruited Asian whitebeams, Micromeles decaisneana (at the corner of David Trail and Lower Asian Way) and Micromeles globosa (on Upper Asian Way near Lam Trail, east of the large Yu’s whitebeam). Both have pomes that resemble Castelvetrano olives. If you like olives and aren’t familiar with that variety, you owe it to yourself to try those buttery Sicilian indulgences. But please don’t try ours. And if this makes you hungry, don’t miss the Garden’s 35th annual Apple Festival, October 17-18.
Micromeles alnifolia
Micromeles aronioides
Micromeles decaisneana
Micromeles globosa
Micromeles karchungii
Micromeles yuana
Sorbus discolor
Sorbus ‘Joseph Rock’
Sorbus macrantha with Pristiphora geniculata (mountain ash sawfly)
Sorbus splendens
Sorbus splendens
Written by:
Douglas Justice
Associate Director, Horticulture and Collections
UBC Botanical Garden
The post October in the Garden 2026 appeared first on UBC Botanical Garden.
There are several “problems” with Sorbus, not least that the common European mountain ash, S. aucuparia, is an invasive species that shows up uninvited in local woodlands, including at UBC Botanical Garden. We keep a close watch on the three dozen or so of our own mountain ashes for this reason. Thankfully, we haven’t seen spontaneous seedlings outside of our irrigated areas, and this suggests that they can’t survive beyond our fences.
Especially this year, visitors may have noticed an increase in leaf “skeletonizing” caused by the mountain ash sawfly (Pristiphora geniculata). Sawflies are small, fly-like wasp relatives, the larvae of which are yellow and brown inchworm-like caterpillars. The small, pink-fruited Sorbus macrantha opposite the Moon Gate in the David C. Lam Asian Garden is annually defoliated in summer and a good example of the voraciousness of this exotic pest. The fact that this little tree continues to rebound, however, suggests that Sorbus are not entirely at the mercy of these caterpillars. Nevertheless, there is much about the sawfly’s reproductive biology and host preferences that we do not understand. All we can do is continue to monitor which species are affected, their locations and the degree of defoliation they endure.
By some trick or unseen circumstance, a few mountain ashes in the Asian Garden remain untouched—including the spectacular red-fruited Sorbus splendens (atop a stump at Stearn and Farges Trails), the tall, elegant, white-fruited Sorbus discolor on Upper Asian Way at Ludlow Trail, and the always praise-worthy, yellow-fruited Sorbus ‘Joseph Rock’ on top of the northwestern slope above the Roseline Sturdy Amphitheatre. Happily, the whitebeams are immune to the ravages of the sawfly. I’ve written at length about whitebeams and mountain ashes (they’re an obvious choice for describing autumn fruit in the Garden), but as recently as November 2024, I described the Asian whitebeams as belonging to the genus Aria. For readers who are keeping track, they are now properly listed under the genus Micromeles. Aria is a genus whose species are restricted to Europe and western Asia, while Micromeles species are native to Southeast Asia and the Himalayas.
An example of the resilience of the Asian whitebeams can be seen in the beautiful orange-fruited Yu’s whitebeam, Micromeles yuana, near the corner of Upper Asian Way and Lam Trail near the entrance to the David C. Lam Asian Garden. But again, I’ve described this species in print many times, albeit first under Sorbus, then Aria and now, Micromeles. Micromeles alnifolia, the alder-leafed whitebeam, is another attractive Asian tree, and one I’ve not featured here. This variable species is widespread in Asia and more commonly known in commerce by its older names Sorbus alnifolia (and Korean mountain ash). This particular specimen, where Handel-Mazetti and Soulie Trails meet, is both elegant and lofty, with tiny orange-red fruits that are visible now, but soon obscured by the similarly-coloured turning leaves.
It has been some years since I wrote about the rare Micromeles karchungii (at the corner of Ludlow Trail and Lower Asian Way). This Bhutanese species produces lozenge-shaped, lemon-yellow and later, apricot-coloured pomes, and this year, they are definitely worth a look, though it has grown tall and the fruits may not be visible until leaf fall. Close by in the Wharton Glade are a couple of pome-laden blueberry whitebeams, Micromeles aronioides. Native to the mountains of southwestern China and Myanmar, this species bears small purple pomes covered in a waxy bloom, which makes them look like blueberries. Finally, rounding out the food theme are two of our green-fruited Asian whitebeams, Micromeles decaisneana (at the corner of David Trail and Lower Asian Way) and Micromeles globosa (on Upper Asian Way near Lam Trail, east of the large Yu’s whitebeam). Both have pomes that resemble Castelvetrano olives. If you like olives and aren’t familiar with that variety, you owe it to yourself to try those buttery Sicilian indulgences. But please don’t try ours. And if this makes you hungry, don’t miss the Garden’s 35th annual Apple Festival, October 17-18.
Micromeles alnifolia
Micromeles aronioides
Micromeles decaisneana
Micromeles globosa
Micromeles karchungii
Micromeles yuana
Sorbus discolor
Sorbus ‘Joseph Rock’
Sorbus macrantha with Pristiphora geniculata (mountain ash sawfly)
Sorbus splendens
Sorbus splendens
Written by:
Douglas Justice
Associate Director, Horticulture and Collections
UBC Botanical Garden
The post October in the Garden 2026 appeared first on UBC Botanical Garden.