Most people fail to notice flowers that are associated with wind pollination because generally they lack showy flower parts. Sometimes people notice the pollen-producing flowers if they are aggregated together to form long dangly catkins or aments. At one time botanists thought that the rather cone-like aments were primitive because they were more like the cones of conifers. But this idea was falsified in the early part of the 1900s. So people notice the long dangly catkins on my filbert, Corylus americana, but fail to see the small but rather showy pistillate flowers. Actually the only part you can see are the bright red, somewhat feathery, stigmas that stick out of the buds to pick up pollen. So here you are both types of flowers, dozens of pollen flowers and 2-3 pistillate flowers. TPP does not like calling them male and female although that is common enough usage, but wrong. Lots of temperate deciduous trees use wind pollination; they flower in the spring before leaves expand an get in the way of pollination. Welcome to the early allergy season.