Curator of Collections, Douglas Justice contributes today’s photos and write-up.
UBC Botanical Garden is renowned for its collection of woody climbers (lianas) primarily because we encourage many of them to climb into the mature conifers in the David C. Lam Asian Garden. The genus Clematis is well represented in all parts of the garden, with wild Asian species representing approximately half of the collection. See this link for a list of clematis accessions in the garden.
Clematis montana var. wilsonii commemorates E.H. (Chinese) Wilson (1876-1930), who introduced vast numbers of plants to cultivation, primarily from China and Japan. This variety from southwestern China is less well known than the more commonly cultivated selections of Clematis montana var. rubens (which are generally larger and pink). Most references describe var. wilsonii as late-flowering (mid to late June) and strongly fragrant, smelling of hot chocolate. The aroma to me is considerably more complex, especially when smelled at close range. A number of my colleagues have been debating the particular components of the aroma—what else do staff at a botanical garden do at lunch?—and we’ve come up with quite a list, including chocolate (of course), but also peppermint, cinnamon, cardamom, carob bean, narcissus (the large trumpet types), oaked Chardonnay, and Advocaat liqueur—the more elusive and volatile components being expressed more strongly with older flowers. Our plants came to us from Guernsey Clematis, the famous nursery founded by plantsman Raymond Evison.
There is considerable disagreement amongst experts regarding the legitimacy and characteristics of the various C. montana varieties; however there is no disagreement on the value of these beautiful climbers to horticulture. The species is generally hardy to Zone 6 or colder, floriferous, and needs no pruning or special treatment. Our plants have taken about 15 years to reach within a few metres of the tops of 25 m tall Thuja plicata (western red cedar). The clematis mode of climbing is well suited to thujas, whose branchlets are the optimal diameter for the twining petioles (and petiolules). Because the leaves and branches of thujas are long-lived, they’re commonly retained near the ground for many years, and this makes starting a clematis up the tree relatively easy. It is important, however, to site the clematis (or any other climber) outside of the drip-line of a western red cedar, as thujas produce very heavy shade and are notoriously greedy when it comes to available water.