Many of the erect shrub Salix (Willow) species can be hard to distinguish from each other.
Useing the Keys and especially the Character Chart Key on the Salicaceae (Willow Family) Page should help.
Are insect pollenated. Both male and female flowers have nectaries to attract pollenating insects.
Male pollen is also brightly coloured red or yellow to attract insects.
Several types of galls can be seen on willows.
These are deformations of plant tissue caused by the physical actions or chemical secretions of insects.
Willow Roses are a type of gall that grows on some species of willow.
It is caused by the larvae of Cecidomyia rosaria.
The larvae through chemical secretions cause the leaves of the bud to grow in a rose petal like fashion.