Plants give off distinctive odors when you crush a leaf or bruise a twig.
By Karl Anderson
When I first began looking at birds, they were abundant enough that there was not much need to learn bird song. Oh sure, there were some songs that were easy to learn. And there were some impossible-to-see birds that could easily be found by voice.
How many people have ever gotten a good look at a whip-poor-will? But with time, birding by ear has become a norm.
Botany people can't use sound to help them identify plants, even though pines and hemlocks may murmur and sedges are said to sigh. But as with bird identification, recognition of plants need not be only by sight. The fragrance of a crushed leaf or bruised twig can be very helpful in identifying trees and herbs, especially at seasons when there are few other obvious guides.
Consider black cherry, for instance. Winter or summer, if you break a small twig and smell the bruised area, you will get a distinct odor of bitter almonds -- that's cyanide, to you. All cherries have it.
On sassafras, the odor of a bruised twig is similar to the "root beer" smell of the root bark. The best field mark for spicebush, summer and winter, is the pleasant fragrance of a bruised twig. It is a common shrub in rich woodlands.
Scrape a twig of black birch and you get a very nice smell of wintergreen. The pith of ailanthus, a common weed tree that can easily be confused with sumac, smells somewhat like peanut butter. The crushed leaves of walnut -- another tree easily confused with other species -- have a distinctive odor. I don't have a word for it -- go find a walnut tree and crush a leaf.
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On non-woody plants there is less need for this kind of identification. In the growing season you usually have a flower or fruit to work with. But everybody knows skunk cabbage and should know wintergreen. It's worth knowing that most members of the mint family (not all) are aromatic, and the fragrances of the individual species are distinctive.
And our four New Jersey "wild onions" are easily distinguished from other, sometimes similar-looking, members of the lily family by their odor.
The aster family has many aromatic members. Sweet goldenrod has foliage that smells like anise, and anything that helps to identify a goldenrod is worth knowing. Camphorweed, in the same family, has crushed foliage that smells vaguely like camphor.
An easy way to tell mugwort from ragweed is to crush a leaf and smell -- the mugwort has foliage that smells spicy, like the bruised leaves of chrysanthemum, but ragweed just smells kind of "green."
Annual wormwood, dusty miller, and absinthe (which you probably won't find growing wild) are all closely related to mugwort, and each has its own fragrance when crushed. Experiment with this. It takes time to learn, but you have the time -- the plant will not fly away.
For information about the Gloucester County Nature Club, visit gcnatureclub.org/.
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