Students of Ethnobotany: Himalayan blackberry, my favorite invasive plant

Foraged blackberries. Photo by Amy J.

This new series of Students of Ethnobotany: Round 2 starts off with a bang and a paradox – a plant that is both wonderfully useful and terribly invasive – thanks to the keen observations of human nature by Amy J.

When I first moved to Vancouver, I was thrilled to discover that blackberries grow wild along the sides of roads and on the edges of forests here.

They typically ripen and are ready to pick and eat in mid-August. They grow on vines with some nasty thorns, but the scratches are a small price to pay for blackberries that are locally-grown, ripened on the vine, and sweeter than any blackberries I’ve ever bought at a grocery store. During the past few summers, I have picked litres of blackberries, eaten these blackberries fresh or frozen, and used them in smoothies, crumbles, pies, and in other desserts (check out a great recipe for blackberry pie bars here: http://joythebaker.com/2009/06/blackberry-pie-bars/). And I’m not the only one. I’ve seen blackberry pickers head to the vines armed with ladders, buckets, and protective clothing. My roommate and her mother pick enough blackberries on the Gulf Islands each summer to make over 100 jars of jam, which they then give away as Christmas presents.

However, I’ve also learned that these blackberries are an invasive species here. Known as Himalayan blackberries, or Rubus discolor, they belong to the family Rosaceae and are native to Europe (not the Himalayas). They were first brought to North America in 1885 by an American botanist, and they now grow all along Pacific Northwest. In case you’re not sure if you’ve actually seen a blackberry vine in Vancouver before, they are quite easy to identify. Their leaves are usually large and serrated along the edges, and are dark green on top and greyish-green underneath. Their stems, or canes, are covered in sharp and slightly curved thorns. In the spring, these plants have pale pink or white, flowers with five petals.

Blackberry canes. Photo from Wikimedia Commons.

As an invasive species, these blackberries pose many ecological problems. Himalayan blackberry vines often out-compete native plants by shading them and producing too much leaf litter. This can exclude understory plants, and prevent shade-intolerant trees, including the Garry oak and Ponderosa pine, from becoming established. Blackberry vines can also grow into dense thickets that block the movement of large animals, trapping them, or limiting their access to water. They may also grow along river banks, displacing deep-rooted native shrubs. This compromises the stability of river banks, increasing the chances of flooding and erosion. Blackberry vines can also provide habitat and food for other invasive species, such as rats, starlings, and feral domestic rabbits.

Himalayan blackberries are also very difficult to control. They grow very quickly – a single stem cutting can grow into a thicket about 5 metres in diameter within 2 years. They spread easily by root and stem fragments, and their seeds are viable for several years. Another problem is that people like these blackberries, and will often even further propagate the vines without realizing that they are contributing to an ecological problem. Thus, like a lot of other invasive species, blackberry growth is fairly widespread across Vancouver.

But all hope is not lost – we can use them as a tool to help raise awareness and educate others. We can use these fresh, free blackberries as a way to get others to appreciate food that is local and in season. We can do our best to avoid trampling other native plants around the blackberries if we do choose to pick them. And of course, we can also take this as a great opportunity to learn more about invasive species in BC. One thing is definitely for sure – Himalayan blackberries win the dubious title of being my favourite invasive species.

References:

http://alienspecies.royalbcmuseum.bc.ca/eng/species/himalayan-blackberry

http://www.bcinvasives.ca/invasive-species/invasive-plants/himalayan-blackberry

http://www.shim.bc.ca/invasivespecies/_private/blackberry.htm