The Original Mystery Plant

Photo by John Nelson

Knowing the right name of a plant is a big step toward understanding it, which makes it easier to determine the best ways to grow it. On the other hand, it is often much easier to develop a strategy for getting rid of a weed if you know what it is you are trying to eliminate.

For information on the free identification service, call 803-777-8196.

The mystery plant is a real show- stopper when in full bloom, although gardeners like it just for the leaves.

It's a member of the bean family, one of the largest plant groups species- wise on earth. More specifically, this tropical bean is a member of the bean subfamily known as Caesalpinioideae and is related to honey- locusts, Gleditsia, the various partridge- peas, Chamaecrista, and the common redbud Cercis canadensis. The mystery plant belongs to a genus with over 500 related species.

It has attractive and remarkable foliage, each leaf with 10- 15 pairs of rounded leaflets. There's always an even number of leaflets, the leaf apex terminated by a pair. These leaflets fold up like praying hands along the leaf midrib at night. Botanists use the term nyctinasty to refer to such night movements by plants.

Flowering stalks are loaded with brilliant gold flowers forming thick spikes that stand straight up, giving the effect of a brightly glowing candle. Pods or legumes follow the flowers and are somewhat angled. They start out green but become brown as they dry.

Bees and butterflies are attracted to the flowers, and wasps, flies, and ants like the fruits and leaves, which give off a sticky, shiny resin. The mystery plant has been used medicinally, but its seeds and foliage are somewhat toxic if ingested in large amounts.

The mystery plant is a tropical species, native to portions of South America, but commonly grown as an ornamental. In warm places, it behaves like a perennial and may actually form a small tree. In colder areas, it dies down to the ground and presumably won't survive unless mulched heavily.

Answer to this week's mystery plant [Answer: "Candlestick plant," Senna alata]

Dr. John Nelson is the curator of the USC Herbarium. To learn more about the Herbarium, call 777-8196. The

department also offers free plant identification.

www.herbarium.org