December in the Garden 2025

Acer macrophyllum

Much as I like to highlight the diversity of plants in flower in the Botanical Garden at this time of year—and there are plenty as I write this in the dying days of November—I have to accept that weatherwise, December is a highly unpredictable month. Flowers and frost normally don’t exactly mix. I am therefore highlighting a few plants in the Garden that are attractive while undressed (as it were). As loyal readers will know, I have approached this subject numerous times in previous blog posts, particularly at this time of year, highlighting the likes of Arbutus, manzanitas, snake-bark maples, Stewartia and Eucalyptus. Still, I’ve missed out on a number of perfectly qualified plants in the past, and to be honest, there are plenty across the Garden from which to choose.

Depending on how closely one looks, tree (or shrub) bark can be very plain, or intricately patterned, by virtue of the nature and age of the bark and its various stretching and fracturing capabilities, or the degree and type of epiphyte growth that colonizes the bark. An epiphyte is any organism, not parasitic, that grows on top of another—algae, lichens, mosses, liverworts and ferns are common bark epiphytes in our climate. Indeed, those plants with exfoliating bark are often seemingly devoid of epiphytes of any kind. Note the “clean” stems of Acer griseum (paperbark maple) (the upper path in the Asian section of the Alpine Garden, and the foot of Kingdon Ward Way in the Asian Garden). Pinus sylvestris (Scots pine) (Roseline Sturdy Amphitheatre) shows this feature, too, though the papery bark is less cleanly shed, and a closer look at the branches that are notexpanding rapidly clearly shows the accumulation of sooty-looking epiphytic growth. The incense cedar, Calocedrus decurrens (above the Garry Oak Meadow Garden) displays striking orangish, platy exfoliating bark that only lifts slowly. Like other plants with exfoliating and or coloured bark, aspect, age and growth stage come into play with respect to the presence of epiphytes. For example, older tissues that do not expand tend to accumulate epiphytes of one kind or another.

In the boggy, acid soil of the BC Rainforest Garden next to the main pond, our native shore pine, Pinus contorta var. contorta, shows finely scaly bark with plenty of lichen encrustation. The much larger shore pine on the west side of the Roseline Sturdy Amphitheatre plantings (in more fertile, better-drained soil) also supports plenty of epiphytic growth, but the fissured and ridged, less scaly bark indicates continuing expansion in stem girth. The two trees both date from the 1970s. One doesn’t have to walk far to run into Acer macrophyllum (big leaf maple) in either the BC Rainforest Garden or the David C. Lam Asian Garden. An exceptionally fast grower, the bark on young trees is smooth, but quickly develops corky longitudinal ridges, which, because of their chemistry and moisture holding characteristics, encourage epiphytic growth. Some of our older trees accumulate “soil” on their larger, more horizontal branches, and so, become festooned with mosses and ferns. These trees are especially important reservoirs of biodiversity.

Located at the periphery of the Carolinian Forest is a planting of Metasequoia glyptostroboides (dawn redwood). The trees are nearly fifty years old with trunks that show a fascinating vertical tapestry of living and dead tissues and organisms in browns and greens, unseen except upon close inspection. If the trees live long enough, the bark will ultimately become scaly, the fibrous longitudinal strips gradually breaking down into smaller and smaller pieces. The same will happen to a greater or lesser degree with Glyptostrobus pensilis (Chinese swamp cypress) on Henry Trail, and other cypress relatives with similar fibrous bark.

The Carolinian Forest Garden itself, although comparatively young compared to most of the Botanical Garden, has a multitude of “barky” trees and shrubs and is worth a stroll to see what wintertime exposes. Betula alleghaniensis (yellow birch) has among the most compelling bark in my estimation. The combination of polished brown bark, pale corky ridges and tattered, paper-like flakes is exceptional. A similar, but unrelated bark belongs to Prunus maackii (birch bark cherry) (in the Peter Wharton Cherry Grove at the eastern end of the parking lot). Despite being “Canada’s maple,” Acer saccharum (sugar maple) is not planted extensively here because of our dry summers and wet winters. Some seedlings thrive, however, and a few in the Carolinian Forest Garden are beginning to show the fascinating tendency of some individuals to produce otherwise smooth bark that cracks into massive plates. These will gradually lift away from the trunk. As far as I know, this feature is unique among maples. Speaking of which, there is plenty more bark diversity to be seen in the maples. So, stay tuned.