I saw these blooming today – a lovely, very abundant parasympathomimetic and smooth muscle relaxant – Garrya elliptica, aka Coast Silk Tassel. This plant is dioecious – meaning that some plants have only male flowers (pollen producing), and the others have only female flowers (seed producing).  The flowers are borne on an inflorescence named a catkin, meaning it hangs down like tassels. This one is a male – you can tell by the yellow anthers.