A common question I ask myself is when encountering a willow with non-lanceolate shaped leaves would be: is it goat or grey willow? To confuse matters even more the two species often hybridize to form Salix. x reichardii, which is something to bear in mind if you are not sure which species it could be. Some general ID tips which help separate the two species are explained below:
Goat willow Salix caprea has leaves that are ovate and generally broadest in the middle with an abrupt tip which bends sideways. Few or no teeth are present on the leaf margins. The leaf buds can be adpressed and slightly spreading from the twig and are red-yellow in colour.
Grey willow Salix cinerea ssp. oleifolia has leaves which are obovate and 2-3 times as long as they are wide. The leaf margins are minutely serrate. The buds are more adpressed to the stem and also red-yellow in colour.