The fascinating pussy willow branches that florists sometimes carry are long lived in water. Sometimes the branches start sending out roots into the water, and even if not, if planted, you may have a pussy willow tree.
Some gardeners will warn you, that the thing about a pussy willow tree, is that you don’t know how big it is going to get. While the official pussy willow trees might be known as Salix discolor, and Salix caprea, there are already two varieties, the former reaching 20 feet high, the latter reaching 25 feet high, and either one could mature into either a tree or shrub. 500 species of willow exist, and many more varieties, and some, categorized under pussy willow willows for the fact that their flowers form before the leaves, can reach just 1-3 feet tall at maturity to 40 feet tall. Identification of willows is notoriously difficult, so a single unlabeled branch from a florist provides no indication of what the mature plant could look like.
No one suspects any harm from a soft pussy willow, but in addition to not knowing its eventual size, it’s also important to be careful in planting because of its root system. Salixes often like very moist conditions, and can have extensive root systems which can stabilize a riverbank, but might also break open a pipe or other water containment system.
Sources:
https://www.bbg.org/news/what_are_pussy_willows_anyway
The New York Botanical Garden Illustrated Encyclopedia of Horticulture, 1981
