Flower buds at the end of a branch of a European ash (Fraxinus excelsior) tree.
From Wikipedia (http://en.wikipedia.org/wiki/Fraxinus_excelsior):
The flowers open before the leaves, the female flowers being somewhat longer than the male flowers; they are dark purple, and without petals, and are wind-pollinated. Both male and female flowers can occur on the same tree, but it is more common to find all male and all female trees; a tree that is all male one year can produce female flowers the next, and similarly a female tree can become male.