NATURALIST
The joy of
A
lichens...
dyeing wool - even today a few people still use small s you walk around towns, villages, woodland, amounts for dyeing. ‘Cudbear’ (Ochrolechia) produced a moorland or the seashore, you may have noticed crimson or purple dye (extracted by soaking it in urine!), small greyish-green or orange-yellow plants growing on while ‘crottle’ (or crotal, Parmelia) gave a brown colour. walls, rocks, roofs, trees, the soil, gravestones, or seashore A few lichens are also used to make perfumes with a rocks; many of these are lichens. Lichens are a close musk-like fragrance. The Saami people who inhabit association or a ‘symbiosis’ between a fungus and an alga in which both organisms benefit. There are many different Lapland traditionally have herds of reindeer which they live with all year round. In these Arctic areas lichens like types of lichens, including over 1,900 in Britain, of which ‘reindeer moss’ (Cladonia) are an important food source around 900 are found in Devon. To fully enjoy them for reindeer. you need to use a magnifying glass, or a jeweller’s loupe Lichens are very slow growing, some growing less than (available from opticians), or better still a X10 hand lens. a millimetre per year, others up to 5mm or more per If you look closely, you will see they are truly beautiful. year. By studying the growth rate of different lichens, it They occur in several forms: crust-like (crustose, tightly is possible to estimate the age of a lichen and therefore attached to trees or rocks), leafy (foliose) or shrubby the age of its ‘host’. For instance, (fruticose); some even produce the stone sculptures on Easter tiny ‘pixie-cups’. They are found As the air becomes Island are estimated to be 400 growing on almost all types of progressively cleaner the variety of years old, while the oldest alpine surface, including metal, PVC plastic, and glass; some even grow lichens increases, until in very clean lichens may live up to 1,000 years! on my car! Lichens can grow in air, such as in Devon, rare species Lichens known as dog lichens very harsh environments such as may be found (Peltigera), also sometimes grow deserts, mountain tops or the high in lawns, as do weeds. Gardeners Arctic. In the Himalayas they have often worry about ‘weeds’ – but they are basically been found growing at 7,400 metres (over 24,000 feet). beautiful wildflowers which appear, according to some Lichens are highly sensitive to atmospheric pollution, gardeners, in the ‘wrong’ place. Many flowers such particularly sulphur dioxide (SO2). In industrial as dandelions, daisies, self-heal, speedwell, hawkbits, city centres, there are very few lichens as a result of buttercups, primroses, nettles, etc, are foodplants for high concentrations of SO2; but as the air becomes insects such as hoverflies, bees, butterflies and moths. progressively cleaner the variety of lichens increases, We can take a positive step towards helping maintain until in very clean air, such as in Devon, rare species insect populations by allowing just a part of our lawn to may be found – such as the ‘string of sausages’ lichen become a wildflower meadow, simply by not mowing it (Usnea articulata) which is fairly common on Dartmoor. for a few weeks until the wildflowers have finished.n As well as being indicators of air quality, the presence of certain species is a sign of ancient woodland. Whereas Anthony John on the rocky seashore there are several lichen ‘zones’; More information: the lowest tide-washed zone is black, looking tar-like The Field Studies Council publishes fold-out charts (available (this is Verrucaria); above this is an orange zone (with from local bookshops) showing many of the common lichens Caloplaca), and higher still is a grey zone with ‘sea ivory’ or go to the British Lichen Society website: (Ramalina). www.britishlichen society.org.uk In earlier centuries, lichens were used extensively in
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