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Do you recognize this mystery plant with unusual brown flowers? Photo by Linda Lee
William Shakespeare; from “Measure for Measure,” Act 3, scene 2, “Indeed, it does stink in some sort…”
Brown flowers? Hmmm. Doesn’t seem very springy, does it?
But this is the time of year for us to recall the incredible diversity of form and function among the flowers around us. Size, shape, scent…and sexuality…are among the very important factors that characterize these marvelous botanical “inventions.”
These flowers appear in the spring (as in now) before the leaves, and they are certainly unmistakable, with a cup-like corolla of six brownish-purple petals and plenty of stamens. This is one of those flowers that have numerous separate pistils, something like a magnolia blossom, and each pistil has the potential of producing a single fruit.
Since it contains both male and female parts, the flower is said to be “perfect,” but when the flower first opens, only the female pistils are working. No pollen.
This makes the early flower functionally female and only able to receive pollen, not to share its own. Pollination is achieved largely by a variety of smallish flies (including fruit flies) and the occasional beetle, attracted to the peculiar scent being put off by the flowers just after they have opened, when the pistils are receptive.
The flowers themselves won’t win any fragrance awards: most people describe the scent as rather stinky, as in yeasty, or even “mousey.” (And then there are those petals, colored like…decaying meat? Could that also have something to do with pollinator attraction?)
After the pistils have been fertilized from the pollen of a different plant, the stamens present will begin to shed their pollen, and the flower becomes functionally male.
Considerable fascinating research has been devoted to its pollination. Dr. Kate Goodrich of Widener University in Chester, Pennsylvania, is one of these researchers. Her ongoing studies have involved comparisons of the flower scent with that of yeasts, or certain bacteria, and thus showing that the flower’s natural scent is in fact mimicking another scent which could also be present in the same setting. Perhaps this strategy is useful in early spring, when there aren’t a whole lot of other pollinators available.
This is a woody species, a slender tree, found in much of the eastern U.S.A., including all of the Southeastern states. The trees have smooth gray bark. At the stem tips, the handsome terminal buds are “naked,” not enclosed by protective scales.
Look closely, and you’ll see embryonic leaves, richly covered with russet hairs. Large, tear-drop shaped leaves tend to be clustered at the ends of the branches. The crushed fresh leaves give off a peculiar, stinky odor (not associated with the flowers), but that doesn’t bother the zebra swallowtail. This beautiful butterfly lays its eggs on the foliage, the only food source known for its caterpillars.
The fruits, indeed, are probably the most well-known aspect of this plant. Ripe fruits have their own array of strong tropical scents not related to those of the flowers, and they are prized by a wide variety of wildlife species, and of course, by humans, too. Perhaps the fruits will be the subject of an upcoming installment.
Answer: “Pawpaw,” Asimina triloba
John Nelson is the retired curator of the A. C. Moore Herbarium at the University of South Carolina in Columbia, S.C. As a public service, the Herbarium offers free plant identifications. For more information, visit www.herbarium.org or email firstname.lastname@example.org.