Bogs are weird, wonderful and totally hostile environments. They are highly acidic, low in nutrients, low in oxygen, water-logged (especially in the lower layers) and, usually, cold.
Because of this, plants have to adapt and develop strategies to survive. In the bogs we have a range of parasitic and semi-parasitic plants, we have plants sharing resources (symbiosis) and we have flesh eating plants. Some plants take on strategies associated with wet rainforests and others with dry deserts.
I was out recently to see what was in bloom in Connemara National Park and to see what adaptations they had undertaken to survive.
The most obvious plant of all is our purple moor grass. This is Ireland’s only grass that actually loses its leaves in winter. This loss of leaves is a strategy for this plant as it pulls in all its nutrients into the plant bulb to bed down for the winter and be ready for growth in spring. This plant colours the landscape with the greens of summer, giving way to a gold red colours in autumn and straw buff coloured hills early the year.
Our two types of bog cotton – multi-headed and hare’s tail – also have ways of living in this acidic environment. This sedge also loses its leaves, but its special adaptation is that it uses it stalk as a bog snorkel to access oxygen that is not available in the peat below.
At the moment, the large bell-shaped Dabeocs heath is in bloom. The other heathers will bloom later in the year, bringing a purple hue to the hills. The heathers’ adaptations are similar to desert plants. They manage their water carefully. Blanket bogs can be waterlogged at times, with dry weather resulting is a crisp and parched environment. As a result, heathers have specialised by having small, needle-like or waxy leaves to prevent water loss. Cross leaved heath has rolled leaf margins and an underside of silky white hairs, which help to reduce water loss from pores in the leaf by trapping air between them.
Bog myrtle has just put out its aromatic leaves, smelling somewhat like eucalyptus. This bog plant, which was traditionally used to ward away midges, has formed a partnership with a fungus to help cope with the nutrient-poor environment. Specialised roots give shelter to fungus, which converts nitrogen into a useable form for them in exchange for nutrients from this plant.
Carnivorous plants on bogs reflect a rainforest-type strategy where all the nutrients are washed out of the system and the plants have to seek food elsewhere. These plants have roots only to take in water and to anchor the plant. They use adapted leaves as animal luring traps, obtaining most of their nutrients from their prey, rather than the soil they grow in. Two examples of this found in Connemara National Park are the sundew and butterwort plants.
Sundews are characterised by the tentacles, topped with sticky globules on their leaves.
These attract insects, which land and become entrapped with sweet, sticky secretions. Butterworts work in a slightly different way. Their basel leaves form a sticky rosette reminiscent of fly paper. In both cases, once the insect is trapped, enzymes are released by the plant to digest it and ultimately absorb the resulting nutrients.
Ireland has 50% of the European and 8% of the world’s blanket bogs. Certainly, in Connemara we are surrounded. I estimate that we in this region have around 2% of the world’s bogs. So take some time to go out and find some of these exciting plants – and don’t forget the midge spray, or you will be wishing that there were more carnivorous plants and less carnivorous insects in this region.