Dwarf Canadian Horseweed

Conzya canadensis

dwarf canadian horseweed

Dwarf Canadian horseweed, photographed at Seacrest Scrub Natural Area, Boynton Beach, Palm Beach County, in August 2014.

Good looks don't carry dwarf Canadian horseweed, Conzya canadensis, but utility does. It is tall and spindly, with long, narrow leaves along its stem. It has a large flower head at the top, but the blooms are so tiny and spare that they barely register with the eye, even in great numbers.

But it is edible, maybe even good-tasting, depending on how it's prepared. Both Native Americans and early European settlers found it useful as a medicine. And in a pinch, if you need a fire and don't have matches, this stuff will do. But first, the botanical basics.

Dwarf Canadian horseweed is a Florida native, found in all but two of the Sunshine State's 67 counties. In fact, it's a native of most of North America. You won't find it in The Yukon. You won't find it in Nunavut, and it's an introduced plant in Alaska. But every other corner of the continent is home for this plant, including Mexico and Central America.

It became something of an accidental tourist not long after Europeans first made note of it. French explorers documented dwarf Canadian horseweed in 1640; by 1653, it was discovered growing in France, some seeds most likely having stowed away on ships carrying beaver pelts. It's now found in Europe, Asia, Australia, Africa and South America.

It can be tall for an herbacious (not woody) plant, hitting five feet or more. It is a perennial and blooms mainly summer to fall. The flowers are white and yellow and resemble a daisy, only in extreme miniature. It starts out with a rosette of leaves at the base and sends out a narrow stem, which has whorls of narrow leaves along its length. As it matures, it begins sending out branches with flowers as small as an eighth of an inch in diameter. The seeds are whispy, tiny versions of dandelion seeds. All in all, the effect is not kind to the eyes, but . . .

Early European settlers to the New World used dwarf Canadian horseweed to make a tea used to treat dysentery.They also used the leaves in bedding as a flea repellant.

Native Americans would boil parts of the plant to make steam for their sweat lodges. They also used it as a snuff to treat colds. Tribes from the Iroquois of the Northeast to the Hopi and Navajo of the Southwest made preparations from horseweed to treat a host of conditions. The Seminoles steamed the leaves and bark and inhaled the vapors as a cough medicine and for asthma. It was used to treat pediatric, gynecological, skin and gastro-intestinal conditions. Hawaiians used it externally to treat sprains.

As noted, it is/was used as food. The Miwok up Wisconsin way pulverized the leaves and used the mash as a condiment. Reportedly tastes like onion. Young shoots can be prepared as greens, and the leaves can be dried and used like an herb. It also has an essential oil that is used in sweets, condiments, soft drinks and cosmetics. And according, to Eat the Weeds, dwarf Canadian horseweed stems are the next best thing to matches if you're out in the woods and need to start a fire. Just find a nice, dry stem and use it as a hand drill.

On the negative side of the equation, it can be weedy, an overly aggresive pest. In farm fields, it can reduce yields by out-competing crops for nutrients. Dwarf Canadian horseweed puts out what are known as allelopathic chemicals that inhibit the growth of other plants. It is a host for an agricultural pest known as the tarnished plant bug, aka Lygus lineolaris, and it can be a host for a viral plant disease called aster yellows. And the leaves and stems contain chemicals called terpenes that irritate the nostrels of horses.

It is a member of Asteraceae, the aster family. Other common names: horseweed, marestail and Canada fleabane.

Photo Gallery — Click on photo for larger image

Published by Wild South Florida, PO Box 7241, Delray Beach, FL 33482.

Photographs by David Sedore. Photographs are property of the publishers and may not be used without permission.