Wicked Plants: The Weed That Killed Lincoln's Mother and Other Botanical Atrocities - Amy Stewart (2009)

LAWN OF DEATH

Who knew grass could be so dangerous? A lawn of wicked grasses could slice your skin with razorlike blades, close your throat with maddening pollen, get you drunk, and poison you with cyanide. One grass even acts as cremator, bursting into flames and sending its seeds and runners over the ashes.

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COGON GRASS

Imperata cylindrical

   

The bright chartreuse blades grow to four feet tall, crowding out everything in their path. The edge of each blade is embedded with tiny silica crystals as sharp and serrated as the teeth of a saw. Roots can travel more than three feet deep, producing barbed rhizomes that pierce the roots of other plants and shove them out of the way in a sinister quest for world dominance.

Some botanists suspect that cogon grass contains a poison that kills its competition, but poison is hardly necessary: cogon grass’s weapon of choice is fire. Thanks to its high flammability, it lures fire into a meadow and sets it loose on the competition, encouraging it to burn hotter and brighter than it otherwise would. (Just one spark from a power saw was enough to turn eight acres in Ocala, Florida, into a conflagration.) Then, like a phoenix rising from the ashes, fresh young cogon blades spring from the charred remains of the roots and grow stronger than ever after the cleansing inferno. When fire isn’t available, wind will do, too: one plant disperses thousands of seeds up to three hundred feet away.

Cogon grass found its way here in the 1940s, when the U.S. Department of Agriculture made the perplexing decision to plant it for erosion control and as grazing food for cattle—in spite of the fact that the grass contains little nutrition and was sharp enough to cut the cows’ lips and tongues. It thrives in the southern United States but has slowly made its way north.

SOUTHERN CUT GRASS

Leersia hexandra

   

A swamp-dwelling grass with sharp blades, widespread in the southe stern United States.

PRAIRIE CORDGRASS

Spartina pectinata

   

Found throughout North America; grows three to seven feet tall with sharp, toothed edges, earning it the charming nickname “ripgut.”

PAMPAS GRASS

Cortaderia selloana

   

Invasive scourge of coastal California. Highly flammable and virtually impossible to kill. Each plant produces millions of seeds. Beautiful feathery plumes are often collected and carried off by naïve tourists, helping spread the seeds even farther.

TIMOTHY GRASS

Phleum pratense

   

A clumping, perennial grass that contains two major allergens responsible for the most severe forms of hay fever; grows throughout North America.

KENTUCKY BLUEGRASS

Poa pratensis

   

A popular choice for lawns and the cause of some of the worst suburban allergies.

JOHNSON GRASS

Sorghum halepense

   

An invasive weed throughout the United States that can reach eight feet tall. Young shoots contain enough cyanide to kill a horse. Death is mercifully swift, usually caused by cardiac arrest or respiratory failure and preceded by only a few hours of anxiety, convulsions, and staggering about.

DARNEL

Lolium temulentum

   

An annual ryegrass that grows alongside cereal crops worldwide. It is often infected by a fungus that if accidentally eaten causes symptoms similar to drunkenness. Two thousand years ago Ovid described a farmer’s ruined fields this way: “. . . darnel, thistles, and a crop impure / Of knotted grass along the acres stand / And spread their thriving roots thro’ all the land.”

Young shoots of Johnson grass contain enough cyanide to kill a horse.

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PAIN FUL

Mala Mujer

CNIDOSCOIUS ANGUSTIDENS

It sounds like the plot of a horror movie: A group of teenagers went hiking in the Mexican desert and came back with a mysterious rash. The next day, one girl went to the doctor complaining of red, itchy spots on her hand. She was prescribed some antihistamines, which should have done the trick. But the pain only got worse. In a few days, a painful red and purple rash in the exact shape of a handprint appeared on her lower back.

FAMILY:
Euphorbiaceae

HABITAT:
Dry desert environments

NATIVE TO:
Arizona and Mexico

COMMON NAMES:
Bad woman, caribe, spurge, nettle

The girl eventually made it to another doctor, who treated her with steroids. The inflammation subsided, leaving patches of brown pigment that faded after a couple of months. But what caused the rash? It appears to have been the work of mala mujer, or “bad woman.” This desert-dwelling perennial has the toxic sap of a euphorbia and the tiny hypodermic needlelike hairs of a nettle. The victim had probably stumbled into a patch of it on her hike, and her boyfriend must have had remnants of it on his hand when he touched her back.

No one knows how the plant got its name, but perhaps those who had been stung by a wicked woman’s wrath recognized the sensation when they encountered Cnidoscolus angustidens—often described as one of the most painful plants in the Sonoran Desert. This perennial shrub grows up to two feet tall and produces small, white flowers; it is easy to recognize because of the distinct white spots on the leaves in the fine hairs covering the entire plant. Although it is not a true nettle, it behaves like one: the fine hairs, or trichomes, easily penetrate the skin and release a tiny dose of their painful poison. One researcher found the pain from the mala mujer’s sting to be so excruciating that he called the trichomes “nuclear glass daggers.”

One researcher found the pain from the mala mujer’s sting to be so excruciating that he called the trichomes “nuclear glass daggers.”

According to a 1971 newspaper account, mala mujer was rumored to be a treatment for infidelity in Mexico; husbands would brew a batch of it into a tea for their wives in order to control their sexual urges. But wives had a much more potent treatment for men who strayed: a hallucinogenic or possibly fatal tea made from the seeds of a datura.

Meet the Relatives These other members of Cnidoscolus genus are sometimes mistakenly referred to as nettles: Texas bull nettle (C. texanus), found throughout the southern United States, and tread-softly (C. stimulosus), found in dry scrublands in the Southeast. Both can bring on nausea and stomach cramps, not to mention intolerable pain.