This week's Mystery plant gives me a good opportunity to brag. I'm happy to brag on Ms. Chanda Cooper, who graduated this past May here at USC with her bachelor's degree in biology and who has been one of our department's most accomplished students. Although technically she was not a student of mine, I hereby claim her as one. Besides, she works for me in the herbarium now. She's busily working this summer on database entry of specimen label data from our collection, her project funded by a recent grant from the National Science Foundation, which will make it possible for us to offer our collection information on-line.

The other day, Chanda brought in this odd-looking leaf and the associated flowers, as a way of stumping her poor old professor. The plant, which grows as an ornamental at her home, is a really interesting member of the bean family.

It's native to central South America, from Bolivia and southern Brazil down into Argentina, where it is well-known and admired. In fact, it's the national flower of both Argentina and Uruguay. In nature, the plants may become trees up to 30 feet tall. This species is widely grown all over the world now as a garden ornamental, and it can tolerate some frost, as long as it gets some protection. Around here, though, it usually only gets to be a shrub, and dies back to the ground each winter. This plant has about 100 close relatives, all in the same genus.

The stems and leaf stalks are wickedly spiny, with very sharp, curving prickles. The leaves are compound, each with three shiny green leaflets. The flowers are extremely showy and quite attractive: Bright red (or red-orange) blossoms appear in large clusters up and down the stem. The flowers have no fragrance at all, but then, being as flamboyant as they are, they must not need any. Each flower has a prominent stalk and a bowl-shaped calyx. The flowers' petals are typical for many members of the bean family, with a large "banner," along with four smaller petals that wrap around the stamens and pistil. In most members of the bean family, such a flower is most often upright, with the banner forming the uppermost or top petal, in the back … the situation you'll see in the individual flowers of kudzu, sweet pea, lupine, clover or soybean, all of which are good "beans". However, our Mystery Plant has its banner petal lowermost of the five petals. The flower is a bit of an oddball in being "resupinate"; that is, during its development, its stalk twists one half of a full turn so that the flower appears to be upside down. Presumably, the banner then acts as a potential landing platform for visiting insects. Considerable evidence, though, suggests that at least in nature, hummingbirds are effective pollinators of this plant.

I'm glad I was able to pull Chanda into the herbarium to work for me. Perhaps she'll bring us another Mystery Plant or two. (Photo by John Nelson.)

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John Nelson is the curator of the 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.