by Amy Stewart
But the South has not surrendered. Aggressive herbicide campaigns, controlled burns, and repeated slashing of new growth can keep kudzu in check. Southerners also fight back by eating the vine that is eating them: fried kudzu leaves, kudzu blossom jelly, and kudzu stem salsa all put a bad plant to good use.
Meet the Relatives Kudzu is a legume; it is related to such useful plants as soybeans, alfalfa, and clover.
DESTRUCTIVE
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.
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.
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.
PAINFUL
HERE COMES THE SUN
Phototoxic plants harness the power of the sun to do their damage, using sap that burns the skin when exposed to light. In some cases, eating the plant or its fruits makes a person more susceptible to sunburn.
GIANT HOGWEED
Heracleum mantegazzianum
This weedy, invasive member of the carrot family looks like the older brother of Queen Anne’s lace. It’s a beefy, sturdy plant that grows over ten feet tall and pushes other plants out of their habitats in streams and meadows. It is also one of the most phototoxic plants you might encounter. One botany textbook shows a round slice of stem placed on a man’s arm; within a day, a circular red welt appears, and after three days, it begins to blister. The wound looks disturbingly like the severe burn a car’s cigarette lighter would cause.
CELERY
Apium graveolens
Another member of the carrot family, this plant is susceptible to a disease called pink rot fungus (Sclerotinia sclerotiorum). The main defense mechanism is to produce more phototoxic compounds to kill off the fungus. Farmworkers and handlers of celery routinely get burns on their skin that show up under sunlight, and people who eat large quantities of celery are at risk as well. One medical journa
l cited the case of a woman who ate celery root and then went to a tanning booth, ending up with a severe sunburn.
BLISTER BUSH
Peucedanum galbanum
This aptly named plant is also a member of the carrot family; its leaves resemble those of celery. The plants flourish in South Africa; tourists climbing Table Mountain near Cape Town are warned to avoid it. Simply brushing past it can cause a reaction, and hikers who accidentally break off a branch may suffer a severe rash from contact with the sap. The rash doesn’t appear for two or three days after contact with the plant and is made much worse by exposure to sunlight. The blisters can last a week or more and may leave brown spots on the skin for years.
LIMES
Citrus aurantifolia, others
Limes and some other citrus fruits contain phototoxic compounds in the oil glands found in the outer rind of the fruit. One medical journal reported on a group of children at a day camp who broke out in unexpected rashes on their hands and arms. Doctors determined that the only children who were affected were those who had gone to a crafts class. They had been using limes to make pomander balls, and piercing the lime peel with scissors spread enough oil on their hands and arms to cause a reaction.
Orange marmalade and other foods containing citrus peel or citrus oil may cause a reaction. Oil of bergamot, a small, pear-shaped citrus, is a popular fragrance ingredient; any citrus-based perfume or lotion could also burn.
MOKIHANA
Melicope anisata syn. Pelea anisata
The mokihana blossom is the official flower of the Hawaiian island of Kauai. Tourists are often presented with a lei made of the dark green citruslike mokihana fruit, which are about the size of grapes. The oils are also highly phototoxic: a few years ago, a tourist wore a mokihana lei for about twenty minutes. Within a few hours, a painful, blistering rash appeared on her neck and chest in the precise shape of the lei. It eventually faded on its own, but the marks remained visible for two months.
HERBAL REMEDIES
A number of plants used in herbal teas, potpourris, lotions, or other concoctions can be phototoxic, although symptoms may not show up for a few days. Medical case studies report reactions from Saint-John’s-wort, rosemary, marigold, rue, chrysanthemum, fig leaf, and others.
A tourist wore a mokihana lei for about twenty minutes. Within a few hours, a painful, blistering rash appeared on her neck and chest in the precise shape of the lei.
PAINFUL
Manchineel Tree
HIPPOMANE MANCINELLA
Tourists vacationing in the Caribbean or on the Central American coast are routinely warned about the hazards of the manchineel tree. As a member of the Euphorbiaceae family, it produces a highly irritating sap that can squirt out of the tree when a twig is snapped off. It also produces a toxic fruit that causes blistering in the mouth and makes the throat swell closed. Even lounging under the trees might be dangerous: rain dripping off them could cause rashes and itching.
FAMILY:
Euphorbiaceae
HABITAT:
Beaches on tropical islands, Florida everglades
NATIVE TO:
Caribbean islands
COMMON NAMES:
Beach apple, manzanillo
The trees are irresistible to tourists. Despite her medical training, a radiologist visiting the island of Tobago was tempted to taste the green fruit that she found lying on the beach. When she took a bite, she found it to be sweet and juicy, like a plum. It took only a few minutes for a burning sensation to start in her mouth. Pretty soon, her throat closed so tightly that she could hardly swallow. The nearest medical remedy, a piña colada, helped a little, but probably only because of the milk it contained.
Captain James Cook encountered the trees on his voyage, and he and his crew also had a nasty encounter with the toxic tree. The men were in need of supplies; Cook ordered them to begin by collecting some fresh water and chopping manchineel wood. Some of the crew members made the mistake of rubbing their eyes, and they were reportedly blinded for two weeks as a result. There’s no record of whether they actually burned the wood, but if they had, the smoke would have been particularly noxious.
Even lounging under the trees might be dangerous: rain dripping off them could cause rashes and itching.
The manchineel tree’s powers have been exaggerated in art and legend. The tree made its way into the 1865 opera L’Africaine by German composer Giacomo Meyerbeer. A heartbroken island queen who is secretly in love with an explorer throws herself under the manchineel tree and draws her last breath, singing:
Your gentle perfume, they say, gives a fatal bliss
Which for a moment transports one to heaven
And then brings on the slumber without end.
Meet the Relatives Part of the Euphorbiaceae or spurge family, which includes a number of other trees and shrubs that produce milky, toxic sap.
DANGEROUS
DON’T LOOK NOW
Many plants that raise a rash on the skin or produce tiny, irritating thorns can also cause vision problems, including blindness. Here are a few of the most egregious examples:
POISON SUMAC
Toxicodendron vernix
Most people in the eastern United States know to avoid poison sumac, a close relative of poison ivy and poison oak. But one young man had to learn his lesson the hard way. In 1836, at the age of fourteen, Frederick Law Olmsted wandered into a patch of poison sumac and got covered in the sap. Soon his face was horribly swollen and he couldn’t open his eyes at all.
It took him weeks to make a partial recovery, but the damage to his eyesight persisted. He couldn’t return to school for over a year, and he once wrote that the problems with his eyes lasted much later into his life. It may be that this time off was just what the boy needed to nurture his interest in the outdoors and that it led to his career as a visionary landscape designer. He wrote, “While my mates were fitting for college I was allowed to indulge my strong natural propensity for roaming afield and day-dreaming under a tree.” Perhaps that year of daydreaming provided the initial inspiration for New York’s Central Park, which he designed twenty years later.
TANSY MUSTARD
Descurainia pinnata
This inconspicuous annual grows to two or three feet tall and produces small yellow blooms in the spring. It flourishes in dry fields and deserts throughout the United States. Its bitter taste discourages people from eating it, but cattle will graze on it, and the consequences can be deadly. Their tongues become paralyzed. They begin “head pressing,” butting their heads up against some hard object like a fence. Finally, the tansy mustard makes them go blind. Given the head pressing, the tongue paralysis, and the blindness, it is impossible for them to eat or drink, and they die of starvation and dehydration.
MILKY MANGROVE
Excoecaria agallocha
This Australian mangrove tree—another member of the highly irritating Euphorbiaceae family—has earned the common name “blind-your-eye” for the temporary blindness, burning, and itching that its milky sap can cause. If the plants are burned, the smoke will also seriously irritate the eyes.
COWHAGE
Mucuna pruriens
In 1985 a New Jersey couple called an ambulance after developing a severe rash. They blamed it on some mysterious fuzzy bean pods they found in their bed. The paramedics developed the same symptoms, and everyone had to be treated at the emergency room. A nurse at the hospital even started itching after touching one of the patients. The apartment had to be completely decontaminated, including cleaning of all carpets and fabrics. The pods were identified as cowhage.
Cowhage is a climbing tropical vine in the bean and pea family. It produces four-inch-long, light brown, fuzzy pods that are covered with as many as five thousand stinging hairs. Even specimens that have been preserved in museums for decades can cause severe itching. If any of the tiny barbs get in the eyes, they can cause short-term blindness.
FINGER CHERRY
Rhodomyrtus macrocarpa
This small Australian tree, also called a native loquat, has long been rumored to cause permanent blindness to people who eat the small red fruits. There were several newspaper accounts of children going blind in the early 1900s, and in 1945 a newspaper reported that twenty-seven soldiers from New Guinea went blind after sampling the fruit. One possible cause is a fungus called Gloesporium periculosum that infects the tree. Australians know better than to take their chances.
ANGEL’S TRUMPET
Brugmansia spp.
A relative of datura, this South American plant can bring on an alarming case of “gardener’s mydriasis,” or excessive pupil dilation. Sometimes the pupil enlarges until it almost fills the iris, making it difficult to see. The effect is so frightening that it can send people to the emergency room in fear of a brain aneurysm.
