pussy willow 
noun
A willow with soft fluffy yellow or silvery catkins that appear before the leaves. Also called sallow2.
- Genus Salix, family Salicaceae: several species, in particular (in the US) the glaucous willow (S. discolor), and (in Britain) the goat willow (S. caprea) and grey willow (S. cinerea).
- In Nebraska the best markets often are for scarlet curls willow, pussy willow and curly willow.
- Weeping mulberry, weeping Siberian pea shrub and weeping pussy willow are often top grafted.
Origin
Mid 19th century: originally a child's word, because of the resemblance of the soft fluffy catkins to a cat's fur.