Little Daisy - Big Problem

A year or so ago I noticed a sprawling, low-growing aster relative cropping up here and there in the yard. I found it completely undistinguished and entirely without ornamental value, but I didn't make more than a half-hearted effort to get rid of it.

Like so many uninvited visitors, it has proven itself a very unwelcome guest in no hurry to leave. It has been beastly hot much of this summer, and I haven't been working in the yard as much as usual. I walked outside a few weeks back and discovered that this seemingly unassuming plant was in the process of overrunning the yard.

A quick ID session revealed it to be Tridax procumbens, or "coat buttons," a noxious weed if ever there were one. Originating in Central America, it has spread worldwide, and infests just about any location with a mild climate. It appears that the only places the weed has established itself in the United States are Florida, Puerto Rico ( I know it's a territory, not a state) and Hawaii, though there have been sporadic outbreaks in other states. However, if it is in north Florida and the Florida panhandle, it must be creeping into southern Georgia and Alabama by now.

Tridax procumbens, habit, ray floret, head

Tridax procumbens has opposite leaves which are arrow-shaped and deeply toothed. The margins (leaf edges) are fringed with tiny hairs. The top surface is felty dark green, with deeply impressed veins. If you bend a leaf to catch the light you will see glittering ranks of  short, stiff hairs that create a texture like fine-grit sandpaper.

The undersides of the leaves are a paler, grayish green with a less scabrous texture. The raised veins are very pronounced, and sport hairs of varying lengths.

The entire plant - leaves, petioles, stems, bases of the flower heads - is hairy. The stems are pale green shading into magenta-brown. The entire head is no bigger than a dime. It has numerous yellow disc flowers and a rather sparing ring of off-white or cream-colored ray florets ending in 3 teeth. (Hence the name "Tridax"). The heads produce thousands of achenes (seeds) whose chaff lets them float away on any breeze.

Leaves, Stems, Heads, Bristles

Triadax procumbens is on the Federal Noxious Weed List as well as the Noxious Weed List of the Florida Department of Agriculture and Consumer Services. It is also on Florida's Prohibited Aquatic and Wetland Plants List. My yard is dry and sandy, but the plant evidently thrives even more given moist conditions.

It's not altogether easy to weed, especially when it is intertwined with groundcovers. It's hard sometimes to find the central point from which the stems radiate outward, especially since the stems are brittle and break easily. You've got to get the taproot, though, or the thing will just regenerate.

In Florida it is illegal to possess, transport or sell "coat buttons." I don't know whether having an infestation on your property qualifies as "possession," but I wanted to be rid of it in any case. I bagged it and disposed of it in the garbage, not the yard waste. Better buried in the landfill than further distributed in county mulch. Though I've won the first round, I am sure I am not through with the war. There must be an established seed bank in the yard by now, and the source of the original contamination likely is still churning out the achenes.

Noxious or not, the plant has medicinal and pest-fighting qualities. It is used in indigenous medicine for a variety of ailments, including wound treatment, stopping bleeding, diarrhea, backache, bronchial congestion, and worms. Dried pulerized leaves and essential oils extracted from the leaves appear to provide some control against insects, nematodes and fungi. Though not native to India, it is used in Ayurvedic medicine. It also has cancer-fighting potential.