Common name: Coat buttons, Tridax daisy
If any plant can be given an MNW or multi-national weed status, it has to be Coat buttons, growing and thriving in all continents. They are perennial herbs that can grow to a height of 2.5 feet. Most of their height is due the flowers that are borne on long, hairy stalks about a foot tall.
Coat buttons have long creeping, green stems that can root at the nodes helping them spread horizontally over large areas. Leaves are small, opposite and pinnate with serrated edges.
Half inch wide flowers held high thin long stalks can help identify Coat buttons, the flowers having 3-6 white ray flowers, and numerous tiny, yellow disk florets. The ray florets have 3 teeth at the edges giving the plant the name, Tridax coming from Tridaktylos, meaning 3-fingered or 3-toed.
Children play with these flowers, by holding on to the stalk, and flicking the flower heads at targets, since the flowers snap away from the stalks very easily. The fruits are tiny and single seeded with a pappus or tuft of hair at one end that helps the seed to travel long distances in the wind. A single plant can produce over 1500 seeds ensuring rapid dispersal to far-away areas.
This is one of the reasons that Coat buttons are considered invasive weeds. Another reason is their capacity to grow almost anywhere; roadsides, thickets, agricultural land, between cracks in paving tiles, edges of pavements and almost any place with a little bit of soil.
They are tolerant to harsh sunlight, extreme shade, poor soil, drought, pollution, salinity and other factors that can hamper the growth of other plants. Even when they are plucked out by hand, they invariably grow right back because of the hundreds of seeds that would have fallen into the soil.
In spite of its notorious status as a nasty weed, Coat buttons have some medicinal properties. They help in treating blood clots, wounds, blisters, fungal infections, skin diseases, liver disorders, gastric ailments and heartburn. They are also good insecticides, and are used as mosquito repellents, by burning their leaves.
Propagation is from seeds.