Salicaceae: Willow Family — Willows & Cottonwood
All members of this family are dioecious, with male and female flowers borne on separate trees. All produce catkins. The male catkins appear yellow or red, depending on the color of the pollen. Female catkins appear green, until they ripen and release the fine, cottony seeds. Distinguishing the willows can be tricky. The shape of the leaf is generally critical. Also, whether the leaves appear before, at the same time or after the catkins is helpful. And the number of stamens in each individual flower in the male catkin is important (this can be seen with a hand lens).