Determining willows
This helps identify willows:
silhouette or habitus: shape of the tree or shrub, height ...
leaf: narrow, broad, hairs ...
catkins: number and shape of stamens, pistil, timing, colour, number of nectar glands ...
bark and twigs: colour, hairiness, shape, buds, lenticels, striae ...
flavour: different bitterness of leaves
color of the root hairs (see appendix 7, 11)
galls: e.g. presence of Rabdophaga rosaria, Stenacis triradiatus, ...
location: soil, light ...
time of day: summer (leaves...); winter (silhouette/habitus, buds...); spring (catkins with or without leaves...)
watch out for abnormal growth conditions such as insect attacks or pollarding and other injuries: normal characteristics (of leaves, for example) become abnormal
in spontaneous storage, two species can sometimes become intertwined
sometimes insects can be a clue; see Appendix 6 Willow lecture