Human Flower Project

Hogweed - Flower of the Cold War

It’s lacerating, it’s impotency-producing, it’s invasive… It’s Giant Hogweed!!

imageTaking the measure of hogweed’s bloom

Photo: King County, Washington

Who’d have guessed that a relative of carrot and Queen Anne’s lace could sterilize goats and scar the faces of children?

This season’s floral horror tale may be found in E.O. Torriero’s fine article about Heracleum mantegazzianum, a.k.a. Giant Hogweed. With blooms big around as doilies and stems stout at sewer pipes, the plants grow to be 15 feet tall. Acquisitive gardeners of a century ago are to be forgiven their eagerness to bring this flowering giant back home, but in doing so they opened a Pandora’s box of lacerating problems.

“It causes burns and bubbly blisters on legs and arms of people who come into contact with its sappy juice. It leaves folks crazed with itching. Discoloration on the skin can last a year.” It’s also the devil to get rid of. Torriero reports that hogweed is even interfering with plans for London’s 2012 Olympics as, by fire, blade, and herbicide, groundskeepers fight back plants that have overrun competition sites. One hogweed plant produces 10-20 thousand seeds each season, so they better make quick work of it, or introduce a new Olympic sport.

imageInvasive plants near Seattle

(hogweed noted in green)

King Co. Noxious Weeds Map

Giant hogweed has been a harrowing nuisance in Michigan where, if you spot one of these botanical Yeti, the state ag department asks that you phone its Hogweed Hotline: 800-292-3939. Things are worse in Washington—and if you think we’re whistling parsnip, then download this big ol’ Hogweed Factsheet from the state and check out the map at right. There are more stands of giant hogweed than coffehouses in Greater Seattle.

Where was this monster born? From its native Caucasus Mountain, we learn, it was introduced to botanical gardens in England, New York and Vancouver, and after putting on grand displays there spread among private ornamentalists as a mammoth conversation piece. Little did these gardners know the talk would turn to shrieks!

Especially intriguing is this excellent story by Peter Walsh from The Baltic Times. He reports from Riga on the animosity Latvane (as Giant Hogweed is known locally) has incurred. Russian ag scientists brought the plant to Latvia in 1968. “The original idea was to use the plant for cow feed because of its high sugar content, according to Kaspars Goba, a farmer and biologist who recently made a documentary film about the Latvane.

“The plan was to cut and grind the plant, store it in silage where it would ferment, and then feed it to the cows in winter. But the problem was the cows didn’t actually like it. Although its sugar content was high, it was still very bitter to taste.” Even hogweed honey, we learn, has a peculiar flavor - sweet and horribly bitter.

The Soviet system, whose science introduced the invader, was able to contain it for awhile with state labor “through a sort of annual culling ritual. Hundreds of people would dress up in plastic clothing to protect themselves from the plant’s acidic sap and hack away with machetes so that the Latvane was at least unable to produce any seeds and spread further. But the situation worsened with the collapse of the Soviet Union in the early ’90s. Agriculture virtually ground to a halt for many years, and the plant was left to flourish.” In the late 1980s, latvane filled about 120 hectares. “Today it occupies more than 13,000 hectares of the (Latvian) countryside.”

Herbicides are effective against Heracleum mantegazzianm, but in Latvia the plant has now spread into national forests, areas where such toxins, with good reason, can’t be used lest they kill off fragile plants and rare animals.

In the U.S., Giant hogweed is a noxious invader of the northern states: May the gardener beware. But in Latvia it’s part of political history, too—a burning reminder of Soviet incursion and a hostile Human Flower Project still.

Posted by .(JavaScript must be enabled to view this email address) on 08/16 at 12:27 PM


I would like to obtain seeds of this plant to grow in a greenhouse. I want to test this plant for insecticidal properties. Next year we are trying other umbels which has similar properties. My idea is to create a botanical insecticide similar to rotenone that can be grown in the north. Do you know where I can get seeds.
As far as the removal of hogweed. What insects and animals benefit from this plant? I know humans should be wary but the same can be said about natives like cow parsnip, water parsnip, water hemlock, etc.  Thanks. Ken

Posted by .(JavaScript must be enabled to view this email address) on 12/12 at 03:03 PM

Dean Ken,

Very interesting. Thanks for writing and letting us know about your research plans.

As for seed, have your tried contacting your local agricultural extension agent?

All good wishes,

Posted by .(JavaScript must be enabled to view this email address) on 12/12 at 03:22 PM

Although its not listed here, we also have it in Ohio.

Noted here on the Ohio State U. web site:

Posted by .(JavaScript must be enabled to view this email address) on 05/24 at 01:42 PM
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