EDITOR’S NOTE: The Georgetown Times features John Nelson’s Mystery Plant series each Friday. You can find the answer to today’s mystery plant in next Friday’s paper.
The answer to last week’s Mystery Plant is: “Thai lime,” Citrus hystrix
In the magic night-time garden, this little weed serves as a knee-high street light, towering above the crickets and toads on a late summer evening. Along its branches are dangling lanterns, and late in the late these shine down, maybe in an imaginary way, illuminating the ground for the little critters, elves and sprites.
This plant is a member of the tomato family…which also includes potato (Irish, not sweet), nightshades, jimson weed, hot peppers, petunias, bell peppers, angel trumpets, and garden brugmansias. This family (known as the Solanaceae) is a big one, with many thousands of tropical and temperate species. The family is well known as a source of many edible species (tomato, potato, eggplant, peppers) but there also some very poisonous members. (Don’t ever eat any parts of an angel trumpet plant!)
Our little herb is an annual weed, and it produces a smooth, angled stem, which is hollow. Its leaves are up to 4 or 5 inches long, and the blades are usually sharply toothed. Small flowers appear in the leaf axils. Each flower bears a non-descript, green calyx, and above that, five yellow petals. The petals commonly have a brownish blotch near the base, and there are five stamens, each tipped with a blue anther. The flower hangs downward as it opens and matures. So far, rather standard as far as most flowers go. But after pollination, the ovary undergoes an impressive period of growth, and swells, forming a cherry sized, spherical, green fruit, which, magically, is invisible. Invisible?
Well, it’s invisible, since it can’t be seen from the outside. While the maturing ovary has been swelling, the green calyx has turned on an even more amazing spurt of growth, to the point that a thin, papery, green husk is formed around the young fruit, almost like a balloon. Botanists say that the calyx is “inflated.” Look closely at one of these, and you will see a small hole at the bottom of the balloon. As it ripens, the fruit changes from green to yellow or orange. The plants bloom from late summer up to the first frost, when they will be killed. The dangling lanterns, though, will remain attached through much of the winter. The fruits are said to be edible and OK for humans (be careful with this!), and are likely to be chewed up by animals, thus dispersing the seeds within.
This species is a native American, widespread in South America, and the eastern USA, commonly seen as far north as Ohio. It is something of a weed, and likes to grow on open roadsides and disturbed places…old gardens and compost piles are favorite areas, as are sand bars along rivers. Plants on particularly “nice,” fertile soil can attain a height of up to two or three feet, but it can bloom and set fruit in poorer places, too, where it usually ends up being shorter.
John Nelson is the curator of the A. C. Moore Herbarium at the University of South Carolina, in the Department of Biological Sciences. As a public service, the Herbarium offers free plant identifications. For more information, visit www.herbarium.org or call 803-777-8196, or email firstname.lastname@example.org.