Giant Hogweed, Heracleum mantegazzianum

Scientific Name:
Heracleum Mantegazzianum
Common Name(s):
Giant Hogweed


Research Summary
: Elias S.
I think the hardest thing about finding the information about this species was the climate and temperature range that it likes. Over all, once I found a great resource, it was pretty easy from there. There were quite a few resources but really only one or two goods ones.

I think that some of the most important information I found and is included in this site is likely about control and its human health impact.

Identifying Characteristics

  • Compound leaf arced deeply cut
  • Up to 5ft wide. 
  • Leaf stalks are spotted, hollow and covered with sturdy bristles.  Most prominent at the base of the stalk.
  • White flowers flat-topped looking like an umbrella up to 2 1/2 ft across.
  • Can produce 20,000 seeds in a year.
  • 1-3 inch diameter for the usual but can reach up to 4 inches in diameter. 
  • Marked with dark purple blotches and raised nodules.
  • 10-20 ft tall.


Taxonomy of Species
   Scientific Classification
 What That Classification Means
 Kingdom  Plantae
 Eukaryotic cells, many celled, don't move, and all members make their
 own food.
 Phylum  Magnoliophyta  Flowering plant.
 Class  Magnoliopsida  A flowering plant with an embryo that bears two cotyledons (seed leafs).
 Order  Apailes  Apailes have clustering flowers at the top of their stem.
 Family  Apaceae  Carrot family, they have thick clusters of tiny five-petaled flowers and
 hollow stems.
 Genus  Heracleum L.
 Cow parsnip.
 Species  Mantagazzianum  Heracluem mantagazzianum

Similar species include: cow parsnip, angelica, poison hemlock, wild parsnip.

Location and Movement
Origin/ Native Range
 Caucasus region of Eurasia (near Turkey).
 This species was planted in Highland Park, Rochester New York in 1917 for its looks. 
Spread of Species
  • This species is hard to control in gardens so when planted it breaks out and travels to other locations.
  • It has also been smuggled to places for its fruit.  Iranian cooks use it in their cultural cooking so they have been smuggling them into places.
  • It has an extensive tap root in its first year making it hard to pull out and it easy for it to take over areas.
  • Its seeds also blow off the top of it and, with hogweed producing 20,000 seeds a year, makes it spread very quickly.
Where is it now invasive?  New York, Connecticut,  District of Columbia, Maine, Maryland, Massachusetts, Michigan, Oregon, 
 Ohio, Pennsylvania, Washington, Ontario, and Vancouver Island in Canada.

Is this species in Maine?
Where has it been identified?
The only area that it has officially been identified in Maine is York County, but the only official resource I could find was dated 2001 so we have reason to believe that has moved even farther north.
How was this species introduced?
  • This species was introduced by breaking out of gardens and traveling here.  
  • It is also being smuggled here by Iranian cooks, which is illegal, so Maine is under investigation.

Natural Environment
 Giant hogweed loves living near creeks, streams, ditches, roads, and various other vacant 
 areas. It prefers moist climates.
Climate and Temperature Range  Hogweed tends to occupy habitats from 160 to 7,200 feet and can withstand January temperature
 ranges from -33 to 61 °F (-36 to 16 °C) and July temperatures from 27 to 95 °F (-3 to 35 °C).

Ecological Interactions  Producer
 Heracleum mantegazzianum uses the process of photosynthesis.
Consumed By
 Cattle and pigs are both cited as consumer of giant hogweed. They are able to touch hogweed
 without any harm..

  • Takes over during the warmer months and due to its extreme size and umbrella top, it steals sun and water from smaller plants causing them to die. This, in turn, could impact plant and animal biodiversity.
  • In the winter, when it dies off, it leaves increased soil erosion on river banks and other steep areas.
  • Giant hogweed is extremely poisonous to humans.  The sap can burn skin when exposed to the sun.  These burns can be so severe that they can cause someone to be hospitalized and if the sap comes in contact with your eyes it could blind you permanently.
  • If giant hogweed did not have such a large impact on humans it probably would not get so much attention and would not be worth the effort to control it.
  • It can be used for cooking which could help your business, but that would break the law because you are not allowed to transport it or plant it in the U.S.
  • Because it towers over and takes the sunlight away from smaller plants, crops could be impacted.

 Biological  No plants are known to control hogweed, but cattle and pigs are known to control it.
 Not allowing it to be traded and not allowing it to be planted or shipped to the U.S.
  • You can cut out the stem from the very bottom but wear long gloves.
  • Pulling out the root-stalk from the very bottom is a difficult  process but can be effective where its roots have not spread to far.
  • When root cutting cut the root around six inches below ground level.
  • Another method to help it from spreading is to cut off the head and seeds.  You want to cut the plant once the flower heads of the seeds have formed but not matured. Once cut put the seeds in a trash bag or something like it and leave out in the sun so the heat of the bag destroys the seeds preventing the plant from spreading.
  • Brush-B-Gone works, as well as many other common chemicals but most wont kill the plant for good.
  • It is easy to use chemicals but they tend to only kill the plant for a little because it just kills the leaves and outside of the plant. Chemicals will not cause permanent control.

Interesting Facts