cat·kin 
(kătkĭn)
(kătkĭn)n.
A dense, cylindrical, often drooping cluster of unisexual apetalous flowers found especially in willows, birches, and oaks. Also called ament.
[From obsolete Dutch katteken, kitten, diminutive of katte, cat (from its resemblance to a kitten's tail), from Germanic *kattuz.]
catkinmale hazel catkins