Homegrown Habitat, February 2024: Sweet Birch
A relatively easy way to identify sweet birch is by its distinctive bark. By Katja Schulz from Washington, D. C., USA – Sweet Birch, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=81223341
Yellow-bellied Sapsuckers love the sap of the sweet birch. Goldfinches, redpolls, and chickadees feed while dangling from the catkins. It’s a beautiful tree that can make your property more attractive to native birds. Homegrown Habitat author Sarah Middeleer explains why. Email your thoughts, comments and questions to her at homegrown@ctaudubon.org.
A simple pleasure in winter is to take note of unusual bark on trees and shrubs. Many examples exist; bark might be peeling, flaking, or striped, and red, green, white, or a beautiful smooth gray, etc. Sweet birch (Betula lenta), also known as black and cherry birch, exhibits shiny, black bark in its youth, with horizontal lines called lenticels. As the tree ages the bark will develop scaly plates.
The bark and twigs emit an aroma of wintergreen when scratched. In fact sweet birch was once used for wintergreen flavoring in many products, but these days the flavor is produced synthetically. Yet one author suggests snapping off a sweet birch twig and gnawing on the end as you enjoy your walk in the woods while cleaning your teeth and freshening your breath. This use is known as a wilderness toothbrush. The tree can also be tapped in spring to make syrup or birch beer from the sap.
Sweet birch is less well known than its hybridized and widely sold cousin ‘Heritage’ river birch – another tree with strikingly colorful and textured bark, and the European white birch, a short-lived magnet for pests and diseases. But sweet birch, native to much of eastern North America, deserves careful consideration, because it can be incorporated attractively into the residential landscape and has great ecological value. It provides food for birds, mammals, and caterpillars. Deer, however, do not care for sweet birch.
Songbirds often eat while dangling from catkins, like this female sweet birch catkin. By El Grafo – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=19614815
The native birches support more than 400 species of moths and caterpillars, leading to their inclusion in the list of “keystone” plants. This category, which identifies the native plants most valuable to wildlife, was established by Doug Tallamy, author, lecturer, and professor of entomology. A complete list of keystone plants for this region, called eastern temperate forests, can be found on the National Wildlife Federation website (see link below in Resources.)
People are not the only ones drawn to birch bark, for birches are favorite feeding trees for sapsuckers. They peck out small holes in the bark, often in straight rows. These holes are known as sap wells, and they attract other bird species for the sap they emit, as well as insectivorous birds who come for the insects that also gather to enjoy the sweet fluid.
Woodpeckers and other songbirds also forage for insect eggs and larvae wintering over in the tree, mining the bark’s nooks and crannies. Come spring many songbirds feed the larvae and mature insects to their nestlings.
Sweet birch can grow rapidly to a height of about 50 feet and a width of 35 feet but in cultivation is often smaller. Its canopy is pyramidal. In April and May dangling, yellow male flower clusters, called catkins and beloved by redpolls and chickadees, mature. They are wind pollinated but are visited by bees and other insects to collect pollen. Female catkins, which resemble small cones, break apart in summer and fall, exposing two tiny, winged nutlets that are enjoyed by many birds and small mammals. My friend Laura Mitchell tells me that goldfinches love the sweet birch nutlets.
The bright-green, toothed leaves of sweet birch spread cooling shade in summer. In fall they turn a glowing yellow, brightening the autumn landscape.
Birches are known as pioneer species, soon to sprout on disturbed land. If this land is allowed to follow the normal process of woodland development (known as succession), other canopy trees will grow up around them. Thus sweet birch can often be found in woodlands, where it provides attractive textural and color interest. Good companion plants include sour gum (also called black gum), witch hazel, and rosebay rhododendron.
But sweet birch is adaptable to different soil types and is salt tolerant. Thus it is also a good choice for rain gardens and roadsides. Consider also using it as a shade tree where you might not have room for a maple or oak. It would also make an inviting grove, along with serviceberry, pagoda dogwood, and ferns, or a more formal planting along an entry drive, perhaps underplanted with mountain laurel and Pennsylvania sedge.
Yellow-bellied Sapsuckers love the sap of the sweet birch (although the tree in this photo is not a birch) .
Resources
Books
Laura Ericksonson, 100 Plants that Feed the Birds, Turn Your Home into a Healthy Bird Habitat, 2022, Storey Publishing
Heather McCargo and Anna Fialkoff, Native Trees for Northeast Landscapes, 2021, Wild Seed Project
Edith A. Roberts and Elsa Rehmann, American Plants for American Gardens, republished in 1996, University of Georgia Press
Jared Rosenbaum, Wild Plant Culture A Guide to Restoring Edible and Medicinal Native Plant Communities, 2023, New Society Publishers
Websites
https://bernheim.org/learn/trees-plants/bernheim-select-urban-trees/sweet-birch/
https://plants.ces.ncsu.edu/plants/betula-lenta/
https://plants.nativemainegardens.org/plants/betula-lenta/
https://www.thespruce.com/sweet-birch-tree-plant-profile-4843256
https://gobotany.nativeplanttrust.org/species/betula/lenta/
https://www.fs.usda.gov/nsl/Wpsm%202008/B%20genera.pdf
https://plants.ces.ncsu.edu/plants/betula-lenta/
https://naturewalk.yale.edu/trees/betulaceae/betula-lenta/black-birch-66
