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FLORA: Sometimes native vines seem invasive

Young creeping cucumber berry is evident before the flower fully opens. Photo by Ken Moore

By Ken Moore
Flora Columnist

When asked by a Flora reader some weeks ago why I did not focus on vines, I didn’t realize that my response would be to become as compulsively focused as I have been lately. Please forgive, forbear and above all, take note.

While notorious exotic invasive wisteria, Japanese honeysuckle and oriental bittersweet are so obviously evident everywhere, the presence of our important native vines can easily slip beneath our cursory visual radar.

Now that I have been focusing on native vines, I am realizing that just about all of them are climbing or sprawling about somewhere on my home turf. From time to time, one or more of these natives become so vigorous that one could view them with the same disfavor we hold for the aforementioned exotics.

Creeping cucumbers are definitely pendulous. Photo by Ken Moore

In Bringing Nature Home, a book we should all read, biologist Doug Tallamy provides perspective on why our native vines may seem out of control. “In the old days, woody vines were restricted to edge habitats where there was plenty of sun. When a tree fell or a fire opened a gap in the woods, viney species would use the trees on the opening edge for support as they climbed into the canopy for sunlight. When the forest gap closed, the seeds from the vines no longer germinated, or if they did, the seedlings were unable to thrive in the shade of the closed canopy. So vines were ephemeral in their impact on the trees of mature forests.”

Today the fragmented forest of human-altered landscapes has resulted in edge habitats everywhere. It may be necessary to step in and modestly curtail the exuberance of our valuable native vines from time to time, like the backyard morning-glory management I described in last week’s Flora. When dealing with the sometimes invasive qualities of our native vines, it is important to keep in mind that the natives provide critical food and shelter for our native fauna, whereas the value of the exotic vines is negligible or nonexistent.

In my wild yard I am managing another exuberant native vine; keeping it in check is easy, less than a half-hour weeding per year. Some of you may recognize this sprawling, small three- to five-lobed leaved vine with tiny yellow flowers followed by miniature watermelon-shaped fruit. It’s called creeping cucumber, Melothria pendula, and the species epithet is descriptive of the very pendulous oval berry.

I well remember years ago when an older friend of mine discovered it in my yard and began consuming it with gusto, but please be advised that though this little cuke is described on some websites as being edible while still green (before it ripens black), I don’t recommend it. My native plant guru, Dr. Jim Duke, does not include it in his Handbook of Edible Weeds and Ritchie Bell and Anne Lindsey, Wild Flowers of North Carolina, advise: “The berries have a strong laxative effect and are considered toxic; do not ingest!”

Be like me and simply observe the miniature flowers and fruits and contemplate what manner of wildlife may depend on this diminutive native vine.

Email Ken Moore at flora@carrborocitizen.com. Find previous Ken Moore Citizen columns at The Annotated Flora (carrborocitizen.com/flora).

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