Catkin

имя существительное [ботаника] серёжка (на деревьях)

Большой англо-русский словарь

Catkin

noun Etymology: from its resemblance to a cat's tail a spicate inflorescence (as of the willow, birch, or oak) bearing scaly bracts and unisexual usually apetalous flowers — called also ament

Merriam-Webster's Collegiate Dictionary