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Smooth Rattlebox
smooth rattlebox
Smooth rattlebox, photographed west of Delray Beach.
smooth rattlebox

There are seven species of rattlebox found in South Florida, only two of which are Florida natives. This one, smooth rattlebox, Crotalaria pallida, is an import from Africa.

All rattlebox species have two things in common: yellow flowers and a pea-pod fruit that rattles when ripe. Smooth rattlebox is an upright plant with leaflets of three, and produces a large, dense spike of showy flowers at the end of the stem. The plant itself can grow to nine feet tall. By contrast, the Florida natives, low rattlebox and rabbit bells, are ground-huggers, and their flowers are less showy.

Smooth rattlebox is found throughout Florida, but moreso from the central Peninsula southward to the Keys. It's also found throughout the southeastern United States, from North Carolina toLouisiana. Smooth rattlebox has become naturalized in warmer places around the globe, including parts of Asia and South America. It is upright, as tall as nine feet, though usually shorter, with a long flower spike atop the stem. The flowers are yellow, sometimes with some red striping mixed in, and appear year-round. It has compound leaves, each with three fairly large, oval-shaped leaflets. It has pea-like pods about an inch-and-a-half long and covered with fine hairs.

Nonnative crotalaria species, including smooth rattlebox were exported around the globe as groundcovers and as a "green manure" crop because of their ability to improve soil nutrients. They are legumes, which means they can take nitrogen from the air and with the aid of certain bacteria, fix to the soil, reducing the need for fertilizers. Smooth rattlebox was especially popular in West Africa and Southeast Asia for use in large-scale agriculture. The problem with crotalaria is that they contain a group of chemicals called pyrrolizidine alkaloids, which are highly toxic to birds and mammals. What's worse, is the effect they have is time-delayed. Eat it and the symptoms might not begin to show for weeks afterward. Smooth rattlebox contains these chemicals, although at a less deadly level than some of its cousins.

smooth rattlebox

There is one species, however, that uses the plant's toxicity to its advantage, and that's the rattlebox moth, Uthetheisa ornatrix. Much like monarch butterflies and similar species use milkweeds to produce both color and poison, the rattlebox moth uses members of the crotalaria family. It's one of the few Florida moths that can actually be described as showy.

At the same time, smooth rattlebox has been used for food and medicine in various places. The seeds are boiled for several hours, wrapped in banana leaves and left to ferment to remove the poisons. The resulting product is called dage. Roasted seeds are used to make "coffee," while the flowers are eaten as a vegetable. It's used medicinally to treat urinary problems, reduce fevers and inflammation. Scientists have found that smooth rattlebox has antibiotic, antifungal and antitumor properties.

Arkansas considers smooth rattlebox, and all crotalaria members to be noxious weeds, but the species is not listed in Florida. Some experts are keeping an eye on this plant to see how it develops. Part of the problem is those pods contain a lot of seeds, giving smooth rattlebox the ability to spread rapidly. Smooth rattlebox was first noticed at Jonathan Dickenson State Park in 1975. In 1992, a survey found it in a few disturbed sites. By 2010, it had taken over 60 percent of the cover along a 4.3-mile stretch of road within the park.

Other common names include shake shake, rattlepod and devil-beans. It is a member of Fabaceae, the pea family.

Photographs by David Sedore
smooth rattlebox
smooth rattlebox
rattlebox moth
smooth rattlebox florida distribution
  United States Department of Agriculture (USDA) distribution maps for smooth rattlebox.  
smooth rattlebox us distribution
Links for Smooth Rattlebox
Institute for Regional Conservation Natives for Your Neighborhood Atlas of Florida Vascular Plants USDA PLANTS Database Center for Aquatic and Invasive Plants
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