MYSTERY PLANT: The flowers of this mystery plant open at night
There's something about a Southern twilight garden in the early summer, especially after a nice dinner and surrounded by friends. Such was my situation one evening last week, after a busy day.
Lengthening shadows, a crescent moon, and chirping crickets provided a background for the day's last song from the Carolina wren up on the wire.
Mr. Wren was chased off by a mockingbird, and we were treated to a melodious original composition (and yet a borrowed one.) by this Southern nightingale. The squirrels were retiring, and now swifts made their appearance, and here and there, in hectic flight, little bats were starting to feed.
Pale hydrangea, foxglove, milfoil, daisies and roses began to brighten the garden borders, but the main event of this crepuscular interlude was a tall herb in the corner, with yellow flowers.
This species grows to be nearly 6 feet tall, producing plenty of blooms toward the top. The stalked flowers have their sepals and petals fused into a long tube, extending well beyond the internal and very “inferior” ovary.
The buds remain tightly closed, all day long, waiting until dusk, at which time they open. Four bright yellow petals appear, along with eight stamens.
Curiously, the pollen produced tends to be in somewhat sticky threads, easily visible on the anthers. A long style is branched at its upper end into four prominent stigmas, thus forming a cross.
As the open flowers age through the quiet night, they produce a sweet, lemony fragrance. The flowers last only a single evening, and shrivel up the next day.
Capsules develop following the flowers; these containing lots of tiny seeds.
Maybe the most delightful thing about this particular species is watching the flowers open up in succession, one by one. You can almost hear them pop. The quiet drama brings plenty of oohs and ahhs from the crowd.
What is most interesting about these flowers is that they do open at night. Generally, night-blooming plants have light-colored flowers, and are often fragrant.
Many of these species are pollinated by moths, which are equipped to probe deep into such flowers in search of nectar.
Our vegetable night owl is native to nearly all of the United States and southern Canada, and is a rather good example of a biennial plant, in that its first year is spent as a more or less flattened rosette of leaves, followed the following year by an upright, leafy, blooming stem.
It is actually quite variable throughout its native range, and botanists over the years have had a terrible time agreeing on how many varieties it should embrace. However its taxonomy might be resolved, this species is easy to grow, and it has been popular in gardens for hundreds of years.
Although it's a native, it is somewhat weedy, so if you are growing it, consider keeping it under control by pulling all but one or two plants. That's all you need, plus a pleasant summer evening.
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, call 803-777-8196, or email firstname.lastname@example.org.
[Answer: “Tall evening primrose,” Oenothera biennis]