River Birch – Betula nigra
The River Birch is easily recognized with its attractive rust and buff colored textural peeling bark that provides the perfect backdrop for its golden hued autumn leaves. The leaves are double serrated, wedge-shaped, and sharp pointed. The lower leaf surface is a lighter color than the upper surface which creates a dazzling display of shimmering contrasts when the wind flutters the leaves.
One of the wondrous aspects of trees, is that they attract a variety of wildlife. Yellow Bellied Sapsuckers drill holes into the bark of River Birch trees in their quest for…you guessed it…sap!
Sap wells made by these Yellow Bellied Sapsuckers attract squirrels, insects, and Ruby-throated Hummingbirds. I keep the color-coded field guide Birds of Pennsylvania by Stan Tekiela on my window sill which is an excellent reference to help identify birds!
The River Birch is the host tree for the Morning Cloak Butterfly. You may observe the caterpillar dining on the leaves as it grows.
Some birds have been known to use strips of the peeling bark in the construction of their nests, and many birds delight in finding insects to eat amid the delicately rumpled bark.
The River Birch is monoecious, with both male and female flowers borne separately on the same tree. On the left below you can see the male flower bud and the dangling male flower catkin. The female flowers are short, conical, and woolly which ultimately form into the green cone shaped fruit called strobiles. The seeds in the fruit, called nutlets, are dispersed by the wind and water once the strobile has become dry and turned brown.
The River Birch is often planted ornamentally, like the tree at Bayne Park. In the wilderness, the River Birch is important as a pioneer species as it quick to colonize disturbed areas and is excellent at controlling erosion. It thrives along river banks and uses a clever method along with special timing to distribute its seeds most efficiently. Most trees (including other birches) produce their seeds in late summer or autumn, but the River Birch is ahead of the game when its seeds ripen in May and June. Perfect timing as the seeds are swiftly moved by the high water which floats them downstream where they can germinate the very same season.
The seeds are also a food source for nuthatches, chickadees, titmice, sparrows, towhees, tanagers, grosbeaks, cardinals and finches.
As you know in April we celebrate National Poetry Month! Although my favorite Robert Frost poem is After Apple-Picking, he also wrote the poem Birches the topic of Birch trees. As he mentions a snow-white trunk in the poem we know he was referring to Paper Birch trees. I recommend the book A Swinger of Birches: poems of Robert Frost for Young People for children ages 4-10 as it includes poems about birds, trees, flowers, people, and land with full color full page illustrations. Adults will enjoy the book Early Poems by Robert Frost.
Thank you for joining us and virtually meeting our River Birch tree at Bayne Park today. Although Bayne Park is currently closed, we hope this virtual experience helps you to feel connected to the trees and we encourage you to visit the trees in person once Bayne Park reopens.
Check back for the next post in this weekly series every Treesday Tuesday!