Blackthorn

The blackthorn (or sloe), Prunus spinosa, is now coming into bloom.
While some of it is fully out, there are nearby bushes where the buds are still tightly closed.

Blackthorn always flowers before the leaves emerge whereas the related hawthorn always flowers after the leaves emerge and about a month later than blackthorn.

Also, blackthorn spreads asexually by root suckers and can create extensive stands of the shrub,  Hawthorn reproduces from seed and generates isolated bushes.