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School Watch


Hogweed: Heracleum sphondylium (Latin name)- Odhrán (Irish name)
Hogweed is a common hedgerow plant which flowers in the month of June. It is similar, but larger than, cow parsley and flowers a month or so later. Hogweed gets its name from the fact thaty up to recently, this plant was collected as pig fodder. Young leaves were also boiled and eaten by humans. The Latin name Heracleum, comes from the legendary Greek warrior-hero Heracles, known to the Roamns as Hercules, who believed it had medicinal value.

Giant Hogweed

Hogweed should not be confused with the plant Giant Hogweed (Heracleum mantegazzianum). Giant Hogweed is an invasive species. It is a native of the Caucasus and was probably introduced to Ireland at the end of the nineteenth century. It is a massive plant easily reaching 12 - 15 feet. Initially this plant was grown on large estates but since the 1960's it has begun to spread throughout the country, especially along river systems.

Giant Hogweed is a beautiful plant when it is in full flower and it is easy to understand why it would be grown on large country estates. But, the plant has been spreading and causing major problems. Giant Hogweed produces a sap that if it comes into contact with your skin will result in the formation of painful blisters and can also permanently impair the skin's ability to filter ultraviolet A radiation.

Many years ago, children used the long hollow stems of Hogweed as peashooters. However, the stems of Giant Hogweed should NEVER be used as peashooters. In fact it is better if neither of these plants are handled at all.

Giant Hogweeds are commonly found along river systems in Ireland. Many can be found along the Tolka in Dublin. The flowers of both the Hogweed and Giant Hogweed are large and flat and are referred to as umbels. Many insect species visit these plants throughout the summer, including the bright orange soldier beetles. The seeds of the Giant Hogweed fall into the river and are carried downstream to germinate. Each plant can produce thousands of seeds, thereby ensuring the spread of this plant as far as possible from the parent plant.

Alien species were originally known as exocitic species. An alien (exoctic) species is one that is introduced into an area where it is not native to. These were probably introduced because they looked different, or had different colours or scents from the native species. But, sometimes these introduced species outcompete the native species and the native species are replaced by the non-native ones. This reduces our biodiversity (variety of living things), reducing the numbers of species of insects visiting the plant and in turn reducing the number of bird species in the area.

1. What is the Irish name for the Hogweed?
2. Give one difference between Hogweed and Giant Hogweed?
3. What is the Latin name for Giant Hogweed?
4. How does the sap of the Giant Hogweed interact with human skin?
5. How would you recognise the flowers of hogweeds?
6. How are the seeds of hogweeds dispersed?
7. What are invasive species?
8. What is another name for invasive species?
9. Why should invasive species be excluded from Ireland?
10. What is biodiversity?



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