Hogweed
Encyclopedia
Heracleum is a genus of about 60 species (depending on taxonomic interpretation) of biennial
and perennial
herbs in the carrot family Apiaceae
. They are found throughout the temperate northern hemisphere and in high mountains as far south as Ethiopia
. Common names for the genus or its species include hogweeds and cow parsnip.
Major species include:
look similar to hogweeds, with white flowers in compound umbel
s, as do some in the daisy family (Asteraceae). Plants confused with Heracleum include the hemlocks (Conium
) and water hemlocks (Cicuta
) which are highly poisonous.
Water parsnip (Sium suave
), which is not poisonous is also similar in appearance.
Yarrow (Achillea millefolium) in the daisy family also has many small white flowers in its inflorescence
, but the leaves are pinnately
separated into small narrow segments.
Biennial plant
A biennial plant is a flowering plant that takes two years to complete its biological lifecycle. In the first year the plant grows leaves, stems, and roots , then it enters a period of dormancy over the colder months. Usually the stem remains very short and the leaves are low to the ground, forming...
and perennial
Perennial plant
A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials...
herbs in the carrot family Apiaceae
Apiaceae
The Apiaceae , commonly known as carrot or parsley family, is a group of mostly aromatic plants with hollow stems. The family is large, with more than 3,700 species spread across 434 genera, it is the sixteenth largest family of flowering plants...
. They are found throughout the temperate northern hemisphere and in high mountains as far south as Ethiopia
Ethiopia
Ethiopia , officially known as the Federal Democratic Republic of Ethiopia, is a country located in the Horn of Africa. It is the second-most populous nation in Africa, with over 82 million inhabitants, and the tenth-largest by area, occupying 1,100,000 km2...
. Common names for the genus or its species include hogweeds and cow parsnip.
Major species include:
- Heracleum mantegazzianum, Giant Hogweed, is a native of the Caucasus MountainsCaucasus MountainsThe Caucasus Mountains is a mountain system in Eurasia between the Black Sea and the Caspian Sea in the Caucasus region .The Caucasus Mountains includes:* the Greater Caucasus Mountain Range and* the Lesser Caucasus Mountains....
, grows to 4-5m tall, and can cause severe phytophotodermatitisPhytophotodermatitisPhytophotodermatitis is a chemical reaction which makes skin hypersensitive to ultraviolet light. It is frequently mistaken for hereditary conditions such as atopic dermatitis or chemical burns, but it is caused by contact with the photosensitizing compounds found naturally in some plants and...
if the sap gets on human skin. The main mechanism for this dermatitis is extreme photosensitivityPhotosensitivityPhotosensitivity is the amount to which an object reacts upon receiving photons, especially visible light.- Human medicine :Sensitivity of the skin to a light source can take various forms. People with particular skin types are more sensitive to sunburn...
, causing severe sunburnSunburnA sunburn is a burn to living tissue, such as skin, which is produced by overexposure to ultraviolet radiation, commonly from the sun's rays. Usual mild symptoms in humans and other animals include red or reddish skin that is hot to the touch, general fatigue, and mild dizziness. An excess of UV...
on exposure to relatively small amounts of sunlight, with rash and blistering appearing within a few minutes: accordingly immediately covering sap-affected skin can prevent the dermatitis in many cases. It has become a serious invasiveInvasive species"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
weed in many areas of EuropeEuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
and North AmericaNorth AmericaNorth America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, after being introduced as a gardenGardeningGardening is the practice of growing and cultivating plants. Ornamental plants are normally grown for their flowers, foliage, or overall appearance; useful plants are grown for consumption , for their dyes, or for medicinal or cosmetic use...
plant. - Heracleum persicumHeracleum persicumHeracleum persicum, commonly known as Golpar or Persian Hogweed, is a flowering plant in the family Apiaceae, native to Iran...
, Persian Hogweed, is similar in size and properties to the Giant Hogweed, and was originally from Iran, Iraq and Turkey; it is known in northern Norway as the TromsøTromsøTromsø is a city and municipality in Troms county, Norway. The administrative centre of the municipality is the city of Tromsø.Tromsø city is the ninth largest urban area in Norway by population, and the seventh largest city in Norway by population...
palm. - Heracleum sphondylium, Common Hogweed, is common in Europe.
- Heracleum lanatum (synonyms: Heracleum sphondylium subsp. montanum, Heracleum maximum), Cow Parsnip, is common in North America
Species
Note that this is a full list of the 187 names described in the genus; the majority of these names are treated as synonyms of earlier-described species by most botanists.
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Heracleum persicum Heracleum persicum, commonly known as Golpar or Persian Hogweed, is a flowering plant in the family Apiaceae, native to Iran... : Persian Hogweed or golpar Heracleum sosnowskyi Heracleum sosnowskyi or Sosnowsky's Hogweed, is a flowering plant in the family Apiaceae, originally native to Caucasus. Now it is a common weed in the Baltic States, Belarus, Russia.... Common Hogweed Heracleum sphondylium, common names Common Hogweed or Cow parsnip, is a herbaceous perennial or biennial plant of the family Apiaceae. It is an umbelliferous plant, in the same group as fennel, cow parsley, ground elder and giant hogweed...
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Similar species
Many plants in the parsley familyApiaceae
The Apiaceae , commonly known as carrot or parsley family, is a group of mostly aromatic plants with hollow stems. The family is large, with more than 3,700 species spread across 434 genera, it is the sixteenth largest family of flowering plants...
look similar to hogweeds, with white flowers in compound umbel
Umbel
An umbel is an inflorescence which consists of a number of short flower stalks which are equal in length and spread from a common point, somewhat like umbrella ribs....
s, as do some in the daisy family (Asteraceae). Plants confused with Heracleum include the hemlocks (Conium
Conium
Conium is a genus of two species of highly poisonous perennial herbaceous flowering plants in the family Apiaceae, native to Europe and the Mediterranean region as Conium maculatum, and to southern Africa as Conium chaerophylloides....
) and water hemlocks (Cicuta
Cicuta
Cicuta, commonly known as water hemlock, is a small genus of four species of highly poisonous plants in the family Apiaceae. They are perennial herbaceous plants which grow up to tall, having distinctive small green or white flowers arranged in an umbrella shape . Plants in this genus may also be...
) which are highly poisonous.
Water parsnip (Sium suave
Sium suave
Sium suave , the Water Parsnip, is a herb belonging to the parsnip family and comes from Africa and some parts of the Northern Hemisphere.- Appearance :...
), which is not poisonous is also similar in appearance.
Yarrow (Achillea millefolium) in the daisy family also has many small white flowers in its inflorescence
Inflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
, but the leaves are pinnately
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
separated into small narrow segments.