Blackthorn (Prunus spinosa)

Blackthorn (Prunus spinosa)

Blackthorn is a small, deciduous shrubby tree.  It grows best in moist, well drained soils and full sun.  It is native to most of Europe, the UK and Western Asia.  It is often referred to as “sloe”.  It has a native lookalike on PEI, Hawthorn (Crataegus spp.).  However, blackthorn spines have buds growing along their length while hawthorn does not.  Blackthorn also starts producing flowers before its leaves are out, and hawthorn does not.

 

IDENTIFICATION

Here are some key features that may help to positively identify Blackthorn:

  • Can grow 6-7 m tall
  • Densely branched and spiny
  • Bark is dark brown, smooth
  • Twigs are black-purple and develop into spines
  • Leaves are small, narrow, oval, slightly wrinkled with a toothed edge
  • Leaves are pointed at the tip and tapered at the base
  • Flowers are white, on short stalks, and bloom singularly or in pairs
  • Flowers appear in March and April, before the leaves are out
  • Flowers mature into blue-black fruits, 1 mm across

Blackthorn is considered a priority species for the PEI Invasive Species Spotters Network.  If you see this plant, please report your sighting.