In the Dead of Winter, A Flash of Fragrance

When leading nature walks in winter, I like to point out that nature is not dead, only resting and waiting for the rebirth of spring. Even now, there are plenty of things to see and do in the winter woods.

On your next outdoor walk, try looking for signs of herbivores. White-tailed Deer (Odochoileus virginianus) are now feeding on the twigs and buds of trees and shrubs. They can eat up to 4 pounds (1.8 kilograms) a day! The twigs eaten by deer are ripped off the plant in a highly irregular way. In contrast, twigs eaten by the Eastern Cottontail Rabbit (Sylvilagus floridanus) are usually bitten off at a 45-degree angle, lower to the ground of course.

Signs of twigs ripped irregularly off the plant by White-tailed Deer (Odochoileus virginianus). Photo by BioKIDS, University of Michigan, http://www.biokids.umich.edu.
Twigs chewed on by Eastern Cottontail Rabbits (Sylvilagus floridanus) are characteristically cut on a 45 degree angle. Photo by BioKIDS, University of Michigan, http://www.biokids.umich.edu/.

Deer will generally avoid twigs that are fragrant, such as Sassafras (Sassafras albidum). They will, however, eat supposedly “deer resistant” plants if they are really hungry. Why are some twigs fragrant? Not only does scent repel vertebrate herbivores, but these fragrant chemicals may have evolved as a defense against insects. It’s an evolutionary game of chess—plants create chemicals to repel predators, but sometimes predators co-evolve and are not harmed by them. Insects may even use these chemicals for their own defense.

We find many of these scents very appealing. Remember the scratch and sniff books for toddlers? Well, you can do that on your next walk. The trick is to identify those trees and shrubs that are scented. Just scrape a small section of the outer bark of a twig to get into the living cambium layer. Doing this on a few twigs will not harm the tree.

Do you like the smell of wintergreen? Try scratching and sniffing Black Birch or Sweet Birch (Betula lenta), as well as Yellow Birch (Betula allegheniensis). These trees have the chemical methyl salicylate, which is used to flavor many products, such as toothpaste and mouthwash. Because it is similar to salicylic acid, with aspirin-like properties, it is also used in topical rubs for muscle pain (think Bengay® cream). Originally, birch beer was also made from this bark. Most of these scents are now produced synthetically.

Black Birch (Betula lenta) bark on a mature tree. Notice the small horizontal lenticels and large, long vertical cracks. Photo by the author.
Black Birch twigs are thin, smooth, medium-brown with whitish pores (lenticels). Leaf buds are alternate, pointed and light brown. Scratch and smell that wintergreen flavor! Photo by the author.

In the northeast, Black Birch is found growing on moist, acidic, wooded slopes, as well as in well-drained rocky areas. The mature bark is dark brown with many horizontal lenticels (pores that exchange gases) divided by many large vertical cracks. The twigs are very thin, smooth, and reddish-brown with sharp, pointed buds.

Yellow Birch twigs also have a wintergreen scent, although this is not as strong as in Black Birch. Yellow Birch twigs are slightly hairy in new growth and are grayer than Black Birch twigs. A mature Yellow Birch tree is easy to identify. Its shiny, yellow-bronze bark, also with dark lenticels, has distinctive peeling strips of curly bark. Yellow Birch grows in moist soils along cooler, north-facing slopes and stream banks.

Yellow Birch (Betula allegheniensis) bark is a rich, golden brown with some curly strips hanging from it. Photo by Peter M. Dziuk, Minnesota Wildflowers.
Yellow birch twigs look very similar to black birch twigs, but can be more grayish and new buds are hairy.
Photo by Peter M. Dziuk, Minnesota Wildflowers.

If you live in a city or near disturbed woodland edges, there is a good chance that the invasive Tree of Heaven (Ailanthus altissima) is nearby. Its smooth bark and very thick, stout branches (as thick as your thumb) are easy to spot. You’ll know it when you smell its twigs. They smell like burned or rotten peanut butter!

Tree of Heaven’s (Ailanthus altissima) stout twigs are as thick as your thumb. Notice the heart-shaped leaf scars. Photo by AnRo0002, CC0, via Wikimedia Commons.

Do you remember the Sherlock Holmes story in which the famous detective smells bitter almonds on a victim’s breath and determines that the person was poisoned? Eastern native trees in the cherry family, such as Black Cherry (Prunus serotina), Pin Cherry (Prunus pennsylvatica), and Choke Cherry (Prunus virginiana), all have a pungent bitter almond odor when scratched. This is because the twigs and leaves contain cyanide! Please don’t ever eat these leaves and twigs.

Black Cherry (Prunus serotina) bark looks like burnt potato chips. Photo by JDMcGreg, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0&gt;, via Wikimedia Commons.
Black cherry twigs are shiny, gray- to reddish-brown and often developing a flaky, waxy, whitish covering. Photo by Peter M. Dziuk, Minnesota Wildflowers.

My favorite fragrances are from trees and shrubs in the laurel family, the Lauraceae, a tropical group with two members here in the north. Sassafras (Sassafras albidum) is found growing on dry, open woodlands and woodland edges and is a pioneer species in fields. Young trees are deep olive green with brighter green twigs. Sassafras tea was once made from its roots, but was found to contain safrole, which has been banned by the US Food and Drug Administration because of its possible carcinogenic effects. Its fragrance is citrusy and fruity. Some people think Sassafras twigs smell like Fruit Loops® cereal.

Mature Sassafras (Sassafras albidum) bark has deep, vertical crevices with horizontal “hatchet marks.” Photo (c)2006 Derek Ramsey (Ram-Man), CC BY-SA 2.5 <https://creativecommons.org/licenses/by-sa/2.5&gt;, via Wikimedia Commons.
Sassafras twigs are green and usually come off of the main trunk at a 60 degree angle. Photo and hand by the author.

Spicebush (Lindera benzoin) is the other northern member of the laurel family. Spicebush grows in moist soils in wooded bottomlands and low swamps, and along streams. Its medium-brown twigs are smooth with characteristic round, reddish flower buds. When scratched, they are strongly aromatic, with a complex citrus, pepper, and pine scent.

Spicebush (Lindera benzoin) is a multi-stemmed shrub with light brown bark and bright white pores (lenticels). Photo by the author.
Spicebush twigs are olive-brown with round, reddish flower buds. Photo by the author.

Although in the midst of our New England winter we all miss the delightful perfume of summer flowers, don’t think that our woodlands are devoid of scent. Take a fragrance walk and you’ll be pleasantly surprised.

Published by Jim Sirch

Jim Sirch is the author of Beyond Your Back Door, a weekly blog about nature in your neighborhood. He is also Education Coordinator for the Yale Peabody Museum, a UConn Master Gardener and board member of his local land trust. As a trained naturalist, he brings a deep understanding of geology, plants and wildlife and how they interact within a particular ecosystem. He holds a B.S in Forestry from West Virginia University, a B.S. from Miami University in Science Education; and an M.S. in Environmental Studies Administration from Antioch University. He is also the 2014 Sigmund Abeles Award recipient from the Connecticut Science Teachers and Supervisors Association for outstanding science teaching and professional development.

9 thoughts on “In the Dead of Winter, A Flash of Fragrance

  1. We use hanging moth ball capsules to keep the deer away from plants we don’t want them to eat. Because we live in a wooded area, the deer are frequent visitors. Just don’t want them eating all the plants.

    Like

    1. I agree Ellen. I have a problem with them too, as most people do. I have been planting small trees and they get hit hard. I try to use deer spray on them but need to refresh that. Maybe a deer fence some day. I don’t like how that looks though – the compound look….. I do plant catmint and mountain mint on edges of flower borders as deer don’t like to step on fragrant plants. Thx, Jim

      Like

  2. Nice job, Jim. I really enjoyed that fragrant walk. Hang out in New York are you in the midst of the big snowstorm? Stay safe! Cheers, Wiz

    Like

  3. Nice job, Jim. I really enjoyed that fragrant walk. Hang out in New York are you in the midst of the big snowstorm? Stay safe! Cheers, Wiz
    (Oops, strange what the microphone picks up from the tv!)

    Like

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: