In the thick of it with bog cotton

THERE’s a road I travel fairly frequently that crosses an area of cutaway bog.

For the past six weeks or so it’s been like driving through a snow-field. The flowers of bog cotton have been so dense the land on both sides of the road has turned pure white. The other day I stopped the car to investigate a bit further.

The botanists prefer to call it cottongrass, not bog cotton, and four species grow in Ireland, though only two are common on bogs. They are common cottongrass and hare’s tail cottongrass. When they’re in flower they’re easy to tell apart. Common cottongrass has many cotton-like flower heads on a single stalk while the other species has a single tuft, like the tail of a hare. The one I had seen turned out to be hare’s tail cottongrass.

The two species occupy different niches on the bog. Common cottongrass grows in wetter places like bog pools or silted up drains. It is adapted to this environment by having air canals in its roots that can pass air from the parts of the plant sticking out of the water to the roots, which may be 60cm down in the wet, anaerobic peat. They act rather like a snorkel.

Hares’s tail cottongrass grows in drier parts of the bog and is one of the main colonisers of drained cutaway. It doesn’t have the breathing tubes but adapts by forming clumps or tussocks. These consist of many plants and, in an undisturbed area, they may be very old, possibly centuries old. The new growth exists on top of the mound of dead old growth and so creates a well aerated and drier environment for itself. The disadvantage is that it can be damaged by a prolonged summer drought.

In winter the leaves of both species die back from the tips and all the nutrients are stored under ground ready for regrowth in the spring. This is an adaptation to the nutrient-poor environment of the bog.

Unlike true cotton, the hairs of cottongrass lack tensile strength. Despite this up to about 100 years ago they were mixed with 25% wool or cotton and made into a fabric that was used in the manufacture of cloth, carpets and roofing felt. It was also used to stuff pillows, make candle wicks and as tinder to start fires.

Nature Table


On warm summer evenings moths are attracted to outside lights which provide a good opportunity to see what species are living in your area. The garden tiger, which is on the wing in July and August, is large, colourful and easy to recognise.

It’s widespread and common in a variety of habitats and its caterpillar, the well-known ‘hairy molly’, is not fussy about its food plants. Adult moths vary slightly in colour and pattern but females are always larger than males.

Most night-flying moths (there are a few day-flying species) are drawn to light, and there are a few theories why. But they are more attracted to ultra-violet light than ordinary white light. This fact is used by biologists who build traps with ultraviolet light.

The moths are funnelled into a box, usually filled with pieces of egg carton, where they are safe until the morning when the scientist checks them. They are released the following evening.


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