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Coat Buttons
coat buttons
Coat buttons photographed in northwest Delray Beach, Palm Beach County, November 2013.
coat buttons  

Coat buttons, Tridax procumbens, might have achieved its pinnacle of fame in May 2009, when the Florida Department of Agriculture named it the weed of the month.

It was a designation well earned, but this scourage isn't just limited to Florida. Far from it. Coat buttons is found in places as far away as Ghana, Mozambique, India, Thailand and the Pacific Islands, including Hawaii. And pretty much everywhere it's found it is a pest.

How big of a pest is coat buttons? The feds have declared it a noxious weed. Two Florida agencies have declared it to be a noxious weed, as has four states, two of which — Minnesota and Vermont — where coat buttons has a proverbial snowball's chance of establishing itself in the wild. They're not taking any chances.

Coat buttons is native to tropical parts of Central and South America and has spread to warmer parts of the globe. The only state where it's managed to naturalize is Florida, mainly from the central part of the state southward. It's been here at least since the 1920s. How it got here is anybody's guess, but an infestation in Laredo, Texas in 1998 offers evidence of how easily it could have established itself. An 18-by-100-foot swath of land along a railroad spur suddenly bloomed with a thousand or more coat button seedlings just after sacks of coffee imported from Mexico were unloaded from a train and moved into a warehouse. The theory is coat button seeds hitched a ride on the coffee sacks.

The amazing part is this: according to the USDA, the plants went from two-leaf seedling to foot-tall plants in full bloom in a matter of three weeks. Just as startling: a single coat buttons plant can produce as many as 500 to 1,500 seeds.

coat buttons plant

An application of Roundup took care of the Laredo infestation, by and large, but that solution would have been a lot more complicated if the infestation had been on or near environmentally sensitive land, a wetland for example.

Coat buttons flowers generally have five petals, some more, some less, usully with three teeth. Leaves are roughtly arrow shaped, oppostite on the stem and the edges are serrated. The plant itself tends to be low-lying and sprawly. Seeds are fluffy, designed to be dispersed by wind. It will grow in lawns, disturbed areas, fields, even cracks in pavements. It's a serious pest in cotton fields as well as corn, sorghum, sugarcane, wheat and other crops. It robs the soil of nutrients, and we can imagine because of the plant's rapid growth that it can choke out crops in newly sown fields.

The interesting thing about coat buttons is its medical potential. The plant has been used in traditional medicine, particularly Indian, to treat numerous conditions. Scientific studies have shown the plant to have antiviral, antibiotic and antioxidant properties, and potential anticancer compounds. Coat buttons has been used to treat skin diseases and heal wounds, as an anticoagulant, fungicide, as a hair tonic, insect repellant and to treat diabetes. Not bad for a plant on the noxious weed list.

Other names include coatbuttons, brittleweed, tridax and tridax daisy. It is a member of Asteraceae, the sunflower family.

Photographs by David Sedore

coat buttons plant florida distribution


United States Department of Agriculture (USDA) distribution maps for coat buttons, tridax procumbens. Note: These maps show coat buttons as native; newer USDA maps show it as a naturalized plant, meaning it's a nonnative that has established itself here.

coat buttons u.s. distribution
Links for Coat Buttons
Institute for Regional Conservation Natives for Your Neighborhood Atlas of Florida Vascular Plants USDA PLANTS Database Center for Aquatic and Invasive Plants
Unless otherwise stated, all photographs are property of the publishers and may not be used without their express permission.