Crop Comments: Wild morning glory has a popular, very edible, second cousin

Throughout spring, the white or light pink, funnel-shaped flowers of wild morning glory graced many roadsides in the Northeast. With help from UConn Cooperative Extension, I’m able to provide information on this pretty flower. The scientific name is Convulvulus sepium (“of hedges” or “of fences”), earning its name because of its climbing tendencies. In addition to being called wild morning glory, another common name is hedge bindweed.

It thrives, aggressively at times, sometimes strangling other plants. Vines of wild morning glory twine around other plants’ slender stems. A couple centuries ago, an English botanist observed one specimen making two revolutions around a victimized plant’s stem in a little less than three hours.

This herbaceous perennial grows up to 10 feet long, branching freely. It can form tangled masses on structures and other plants or just grow along the ground. Stems can have hairs (or not), with young vines displaying red tinges. Leaves are arrowhead-shaped and, like the stems, may or may not have hairs on the upper and lower surfaces. Tips are pointed, with leaves two to four inches long; leaf base is angular, with lobes resembling the shape of dog’s ears.

Flowers are produced singly, with white to light pink petals. In the Northeast, C. sepium flowers normally are present from mid-May through September, with two to four seeds present in a capsule. The dark brown seeds are shaped like little citrus segments, surviving in soil for up to 30 years.

This plant is confused with other vines, especially field bindweed (C. arvensis). Field bindweed has smaller leaves with a more rounded tip, and bases that are rounded and pointed, but not cut off squarely (like the “dog’s ears” of wild morning glory). Although quite attractive, this plant is aggressive enough to be designated a “noxious weed” in some states.

To get rid of these vines, the best method, on a small scale, is hand pulling. This may not be a one-time chore, because new plants can grow from rhizomes, which tend to be shallow and capable of becoming 10 feet long. A 1974 greenhouse study reported that C. sepium has allelopathic tendencies. This means that exudates from the roots inhibit other plants, which helps explain its ability to take them over.

Another, more labor-intensive weed control tactic that reportedly kills these vines is to unwind them from their stem or support (again, on a small scale).

Several insect species visit C. sepium flowers for nectar, acting as pollinators. These include bumblebees, carpenter bees, mallow bees, squash and gourd bees and (naturally) the morning glory bee. Scientists commonly believe that flowers on the same vine are infertile (they need to cross-pollinate).

Leaves are often eaten by common plume moth caterpillars as well as tortoise beetles. Although very few mammalian herbivores prefer these plants, bobwhite quail and pheasants commonly enjoy their seeds. Stalks and chutes are sometimes consumed by humans, offering a sweet taste after being washed and steamed.

This last comment leads me to introduce Ipomoea batatas, a dicotyledonous plant that belongs to the bindweed or morning glory family, Convulvulaceae. Its large, sweet-tasting, tuberous roots make it a root vegetable. It’s commonly referred to as sweet potato, the second cousin mentioned in my title. But wild relatives of sweet potato should not be eaten in large quantities because of possible laxative effects. These versions have been used in traditional medicine as diuretics. Large quantities of their seeds and roots can be slightly toxic, but pigs have consumed them without problems.

Interestingly, field bindweed is technically edible, but its roots are not the most commonly harvested part in summer. In traditional use, the tender young rhizomes (underground stems) are gathered in early spring, where they often contaminate sorghum fields in China. They are then mixed with cracked wheat and ground beans to make a thin gruel.

Sometimes sweet potatoes are confused with yams. A yam is a starchy root vegetable and stem tuber belonging to the yam family (Dioscoreaceae), which is also connected with lilies. It’s native to Africa and Asia, with most crops hailing from African countries. Yams are grown underground, and though they might look like large potatoes, they’re not. On the outside, the skin of a yam somewhat resembles tree bark. It’s rough to the touch with a brown exterior and white or pale yellow flesh on the inside. The yam isn’t entirely edible: the leaves and stems must be removed, and yams need to be peeled and cooked before being eaten. They’re toxic when eaten raw. No yams belong to family Convulvulaceae, the one claiming all sweet potatoes.

In his textbook “Weeds: Control Without Poisons” (Acres USA, 1996), Charles Walters explains that the perennial C. sepium reproduces with both seeds and shallow creeping roots. He calls it a blood brother to field bindweed and morning glory, C. arvensis. Sister Sepium is also known as “climbing false buckwheat,” growing almost everywhere, even on eroded, well-drained hillsides.

According to Walters, “Bindweed reflects improper decay of organic matter (OM), as well as excess accumulation of heavy soil metals. A high germination rate of the weed may be caused by a concentration of cattle stomping OM into the ground. Morning glories function best in the presence of humus materials and a dysfunctional decay system.” Such conditions can occur within soils of high cation exchange capacity (CEC), like clays, as well as low CEC soils, like sands and with varying ranges of soil OMs.

Those conditions almost always occur in soils that limit fermentation and optimal breakdown of organic residues. Quoting Walters directly, “Correct these (above) soil limitations through pH management, and the bindweed/morning glory syndrome becomes completely dispersed. No herbicide chemical or fertilizer material can replace good management.”

This is my own observation: if magnesium is deficient (documented by soil test), Epsom salt (magnesium sulfate) broadcast at 200 lbs./acre has been shown to greatly discourage both wild morning glory and bindweed in row crops. I have used this management approach myself and gotten others to successfully practice what I preach.

by Paris Reidhead