knots is a form of:

Catkin



noun
1.
(កសិកម្ម) ផ្កាចង្កោម
ENGLISH MEANING
noun
1.
An ament; a species of inflorescence, consisting of a slender axis with many unisexual apetalous flowers along its sides, as in the willow and poplar, and (as to the staminate flowers) in the chestnut, oak, hickory, etc. -- so called from its resemblance to a cat's tail.