Years ago I took a course on “How to identify trees and shrubs in winter” at the Royal Botanical Gardens in Hamilton. At the time, the instructor told us that it was easiest to learn trees and shrubs in winter and I agree with him.
Buds from one species are completely different from those of another and twigs are easy to collect. In the winter of 2016 I collected and photographed buds from over 120 species. Click on “Winter Buds” on the homepage to see the complete list.
Here are a few examples: