LAST week on this page I mentioned that on a trip to Kerry I had found a plant called the large-flowered butterwort and that it was carnivorous.
This prompted a bit of feed-back.
Some people were amazed there were carnivorous plants growing wild in Ireland because they associated them with the tropics. Other people wondered if the Venus flytrap, the best known carnivorous plant, grew wild in Ireland.
In fact there are 11 species of carnivorous plant growing wild in Ireland, 10 of them native and one introduced, but the Venus flytrap isn’t one of them. It’s native to a small area that straddles the state line between North and South Carolina in the United States, though it has been introduced in other places.
It’s also quite widely available as a novelty house plant in Irish garden centres. If you buy one for your conservatory remember it’s not a tropical plant and to flourish and have a long life it needs a period of winter dormancy in a cool place.
Three of the native carnivores are sundews.
They’re small red and green plants which get their name from hairy tentacles around the edges of the leaves that are coated with glue for catching insects and other small creatures. When the prey gets stuck the leaf slowly curls round it and digests it.
The commonest is the round-leaved sundew, the largest the long-leaved. The other one, the intermediate sundew, is rather rare and confined to a few locations in the west of Ireland.
All three are bog plants that have been forced to take up the flesh-eating way of life because of the lack of normal nutrients in the peat and the intense competition from sphagnum moss. They average about five insects or small spiders a month.
There are also three native species of butterwort. They don’t have the tentacles of the sundews but the surface of their pale, yellowish leaves is greasy like a pat of butter.
When a small insect sticks to this surface the edge of the leaf rolls over to digest it. The large-flowered butterwort has a spike of magnificent purple flowers, like over-sized violets, in May and June and is only found in rocky parts of Cork and Kerry.
The common butterwort is similar but smaller and is commonest in rocky and boggy parts of the northwest. The pale butterwort has small, pale pink flowers and is also found mainly in western counties.
The bladderworts have a totally different approach when it comes to trapping their prey. They’re small, rootless, free-floating aquatic plants that are mainly found in bog pools.
They create a vacuum inside a digestive chamber or bladder.
When something like a water-flea swims by they can spring open the door of the chamber, the vacuum sucks the prey inside and the door closes behind it. The whole process can take as little as 1000thof a second.
There are four native species of bladderwort, so that makes up the 10 native carnivorous plants. But in 1906 pitcher plants from south eastern Canada were introduced into a bog in Co Roscommon, and they have been established in several other midland bogs since then.
They have gaudy red and green leaves that form a cone-shaped cup or pitcher.
This fills with rain water and digestive juices.
The plant then produces alluring scents to attract flying insects. When they land on the inside surface they become trapped by downward pointing hairs and the plant drugs them with a narcotic.
* dick.warner@examiner.ie
a d v e r t i s e m e n t
This appeared in the printed version of the Irish Examiner Monday, September 28, 2009
