Family: Rosaceae

Common name: Trailing blackberry

E-flora BC: https://linnet.geog.ubc.ca/Atlas/Atlas.aspx?sciname=Rubus%20ursinus

Wikipedia: https://en.wikipedia.org/wiki/Rubus_ursinus

Rubus ursinus, trailing blackberry, is sometimes called ‘the Devil’s shoelaces’ because its thin stems, trailing and arching slightly above the ground, tend to trip you as soon as you step off a walking trail. Like many other plants on our Botany list, trailing blackberry is quite adapted to a range of habitats. It grows most luxuriantly in lightly shaded sites with a bit of extra moisture, but it stays alive and spreads also in very dry, exposed sites. The species name ‘ursinus’ is derived from ‘urs / ours’ the word for bear. Bears probably enjoy the sweet flavourful berries of this plant as much as humans do – they are one of our best tasting berries.

The 3-lobed leaves and trailing habit of Rubus ursinus. In this species, male and female flowers are borne on separate plants, here we see a female fruit-bearing plant. Photo credit: Lynda Stevens
The compound leaves of trailing blackberry have three leaflets each. The flower shown in this image is male – it has only stamens (male structures). Photo credit: Lynda Stevens

As the common name suggests, the stems of trailing blackberry trail along the ground. They are quite slender, typically less than 1/2 inch in diameter, with fine, sharp prickles. The surface of the stem is usually covered in a fine layer of wax crystals that impart a greyish-green hue. Plants growing in very sunny spots can have reddish stems.

Specimens of trailing blackberry growing in light shade often have ‘glaucus’ stems, meaning that they have a greyish-blue hue , as illustrated in this photo. The greyish hue is due to a layer of crystalline waxes on the leaf surface. Photo credit: Kerry Neijstrom
The waxy layer is easily rubbed off if you touch the stem. You can tell that the shiny green stem has been revealed in the center of this photo. Be careful if you try this on your own, the prickles are very sharp! Photo credit: John Seiler

You may not see flowers, nor fruit, of the trailing blackberry when you look for them in the fall semester, but we’ll show you some images for your future reference. As members of the Rosaceae family, trailing blackberry flowers have five each of sepals and petals. Compare the images below to those of Rubus parviflorus (thimbleberry), Rubus bifrons (Himalayan blackberry) and Rosa nutkana (Nootka rose), you’ll see the resemblance in flower morphology.

Rubus ursinus has ‘imperfect’ / unisexual flowers. A given plant carries either male or female flowers. Here, a male flower is shown. Note the large number of stamens that is typical of flowers of the Rosaceae family. Photo credit: Lynda Stevens
Female flowers of R. ursinus. Note the absence of brown-tipped stamens. The many thin ‘stalks’ in the center of each flower are the stigmas and styles of the female ovaries. Each little stalk (stigma and style) leads to a single ovule that contains a single egg. Photo credit: Lynda Stevens
Berries in different stages of ripeness on a female trailing blackberry plant – generally the fruits are deep purple to black when fully ripe. Compare these fruits to those of garden-variety raspberry plants, and to the fruits of thimble- salmon- and blackberry – all members of the genus Rubus. Photo credit: Lynda Stevens

The fruits of trailing blackberry are enjoyed by anyone who tastes them, and have been / are collected and eaten fresh or dried as food by First Nations people in our area. Vegetative parts of the plant were collected and processed into different types of medicine.

Sometimes people are unsure as to whether they’re looking at a trailing blackberry or Himalayan blackberry (Rubus bifrons). Try to count the number of leaflets and look at the overall stature of the plant. Most Himalayan blackberry leaves have five leaflets (except those on flower-bearing shoots), most trailing blackberry leaves have three leaflets. The Himalayan blackberry plant is robust and usually clambering over other vegetation, it has large, hard and sharp prickles that are wide at the base. Trailing blackberry have dense and sharp, but slender prickles. The stem of trailing blackberry is usually covered in a waxy layer that can be rubbed off.