Black Cottonwood (Populus balsamifera ssp. trichocarpa)
It’s not freshly-washed bears that smell so sweet these days – it’s cottonwoods budding in Whistler’s valley bottom.
Cottonwoods invoke strong feelings and it seems you either love ‘em or hate ‘em. Most people enjoy the smell (even if they don’t know the source), and many admire the beauty of the huge cottonwoods along our creeks and rivers. Birds and other animals also appreciate cottonwoods as their source of habitat.
Foresters and others show cottonwoods a little less affection. Cottonwood has a low timber value, and its sticky bud casings, cottony seeds, and propensity to fall over don’t tend to endear it to its neighbours.
Cottonwoods are probably the fastest-growing trees in B.C., with some young trees growing up to 3 metres in one year. These sprinters are perfectly adapted to taking advantage of the aftermath of floods, fires, and logging. They don’t grow well in shade and are old at 100 years.
Whistler once held the record for the largest cottonwood in BC. The late Randy Stoltmann found it on the south side of 19-Mile Creek, about 300 metres downstream of the highway. In 1986, this tree was 41.2 metres tall and 6.9 metres in circumference. Slightly bigger trees have since been reported elsewhere, but there’s no doubt cottonwoods grow very big here.
Cottonwood is the only native poplar in Whistler. Trembling aspen is also a poplar and is often planted here, but its closest natural occurrence is in Pemberton. Cottonwood can be distinguished from aspen by its round stems (versus the flat stems on aspens) and the deeply-furrowed, whitish bark on older trees.
First Nations people in our area once regarded fresh cottonwood cambium as a delicacy, and harvested it about this time of year. Bees have a more esoteric use for cottonwood. They collect the sticky resin to protect their hives from mice and other unwelcome visitors.
Cottonwood gets its common name from the white-haired seeds that parachute down in the thousands in early summer. The accumulation of white fluffballs can be so deep some may be fooled into invoking the 20 cm rule and heading for the ski hills.
May 31 – Sunset nature walk. Meet at the base of Blackcomb in front of Merlin’s at 6:30, rain or shine.
June 4 – Hanging baskets using native plants. 10:00 a.m.
Website of the week: Big Trees of BC (www.elp.gov.bc.ca/rib/wis/cdc/trees.htm).
Written by: Bob Brett