dogwood

Dogwood (Cornus sp.) can be found at a number of locations in the area, but it is often planted. However I noticed this morning, setting out in a northerly direction, a single specimen growing in a hawthorn hedge, which presumably is spontaneous. It's probably the common Cornus sanguinea, but I don't know how to distinguish this from Cornus sericea and Cornus alba, except by fruit, and this specimen won't be fruiting this year, as it has no flowers currently.