Characteristics for Identifying Trees – Catkins

Well, today is the first day of spring. We’re expecting another inch or so of snow tonight. Will it ever end? Well, when it does, the first signs of spring may not be leaves emerging from trees, but the flowers of wind pollinated trees. At Dennis Panu Arborist, we use many tree characteristics to identify trees, but, botanically speaking, the most accurate way to identify trees to species is through their flowers. In the spring, several plant families in New England produce their flowers in structures called catkins: small clusters of tiny flowers bearing a resemblance to a cat’s tail. (“Catkin” comes from an old Dutch word for “kitten.”)

Most people think of flowers as being colorful and showy. While this is true when flowers need to attract pollinators like birds or insects, trees with catkins are typically wind-pollinated. Each catkin is made up of many tiny inconspicuous flowers. Most catkins contain male flowers, producing prodigious amounts of pollen, but some trees also have female catkins. In order to facilitate pollen distribution, catkins often appear early in the spring before the tree produces leaves which would block the wind.

If you live in Massachusetts or Connecticut, keep an eye out for trees from these families as they produce flowers in the spring:

• Birch family (Betulaceae)
Trees in this family include birch, hazelnut and hornbeam. Look for the pendulous male catkins dangling in the wind early in the spring. Birch family trees also have their female flowers in catkins, which are much smaller then the male catkins and fixed on the branch. (An exception is hazelnut; the female flowers occur singly on the branch to accommodate the large nuts.) Betulaceae trees are monoecious (“one house”), meaning that male and female flowers occur on the same tree. The species of birch can often be determined by the number of catkins in each cluster. Here are some photos of birch catkins.

• Willow family (Salicaceae)
Including willow, cottonwood and poplar, trees in this family are dioecious (“two houses”), meaning that male and female catkins appear on separate trees. It can be difficult to tell the tiny male and female flowers apart, but an arborist can make the distinction. The fuzzy “pussy willow” you see in flower arrangements is a classic example of this family’s catkins. Also, the drifts of snowy seed pods floating through the air in spring are a sure sign that a female Salicaceae tree is nearby.

• Oak and beech family (Fagaceae)
Everyone recognizes the acorns produced by oaks (or, less commonly, beech nuts), but keep an eye out for these trees’ flowers. Oaks and beeches produce hanging male catkins for wind pollination. Female flowers are not in catkins, however, but occur singly or in pairs in the leaf axils (where the leaf meets the main branch). Fagaceae trees are monoecious, with both male and female flowers on the same tree.

For help identifying trees on your Massachusetts or Connecticut property, or for other tree care service questions, contact Dennis Panu Arborist today.