Hainault Forest Website

Lichens

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Foliose lichen Evernia prunastri (Oak Moss Lichen) on Hawthorn twig. LICHEN ZONE 5

 A fruiticose lichen Ramalina farinacea  (Ragged mealy lichen) on Hawthorn twig.

LICHEN ZONE 5

Foliose lichen Hypogymnia physodes (Puffed Shield Lichen) has hollow lobes. On hawthorn bark.       LICHEN ZONE 4

A lichen is an association between a fungus and either an alga or cyanobacterium, both of which contribute the photosynthetic pigment chlorophyll,  necessary for photosynthesis - being the conversion of carbon dioxide and water to complex carbohydrates in the presence of sunlight. What the benefits of such partnerships is little understood and is described as mutualistic.

Lichens are very sensitive to air pollutants such as sulphur dioxide. In the fifties and sixties, the lichen flora in Hainault Forest was mainly represented by Lecanora conizaeoides - a grey powdery covering on the trunks of trees. This species is extremely tolerant of high levels of sulphur dioxide which were borne by the dominant south-westerly winds blowing over the country from industrial areas. This species was absent from Western Scotland where relatively clean air prevailed.

Comparison of levels of sulphur dioxide pollution with the lichen species present in an area, led to lichens being used to monitor air quality by D.L.Hawksworth and F.Rose in 1970. See scale below.

Today, after enactments of Clean Air policies, lichens are gradually returning to Hainault Forest and are to be found growing on the trunks and branches of trees and shrubs, and other substrates.

 Foliose lichens Xanthoria parietina (Common Orange lichen) (left) showing fruiting bodies and Physcia ascendens (right) on hawthorn twig - note the long black cilia on the lobes.   

BOTH IN LICHEN ZONE  4

 Foliose lichen Xanthoria polycarpa showing numerous fruiting bodies, on hawthorn twig, forming a compact cushion.

LICHEN ZONE 4

Foliose lichen Physcia ascendens with fruiting bodies  on bark of aspen.  

LICHEN ZONE 2

Foliose lichen Xanthoria candelaria on oak bark. Note the crimson reaction with KOH Potassium hydroxide LICHEN ZONE 5

Foliose lichen Candelaria concolor on old oak tree. KOH reaction negative.

LICHEN ZONE 7

Crustose lichen Diploicia canescens on bark of willow.  LICHEN ZONE 3

Foliose lichen Physcia tenella      

LICHEN ZONE 4

Foliose lichen Phaeophyscia orbicularis on oak bark. LICHEN ZONE 2

Foliose lichen Physcia tenella with fruiting bodies.

Foliose lichen Flavoparmelia [Parmelia] caperata (Wrinkled shield lichen) on aspen bark  LICHEN ZONE 6

 Foliose lichen Melanelia [Parmelia] subaurifera on oak bark.  LICHEN ZONE 4

Foliose lichen Parmelia sulcata (Netted Shield Lichen) on oak bark.  LICHEN ZONE 4

Leprose lichen Lepraria incana on oak bark.  A pale green powder.

LICHEN ZONE 2

Crustose lichens Rinodina gennarii (black) and Candelariella aurella (orange) on sliver of fencing on Foxburrows farm.

LICHEN ZONES 3 and 2

Crustose lichen Lecanora symmicta on hawthorn twig LICHEN ZONE 7

Foliose lichen Physcia caesia (Grey Warted Lichen) on  Black poplar bark.

LICHEN ZONE 3

Squamulose lichen Cladonia fimbriata (Slender Pixie-cups lichen) on rotting moss covered wood.     LICHEN ZONE 3

Fruiticose lichen Usnea subfloridana (Beard lichen) on willow bark by the lake.

Squamulose lichen Cladonia chlorophaea on moss covered rotting log amongst heather in heathland area. LICHEN ZONE 4

Squamulose lichen Cladonia coniocraea on rotting hornbeam log.   LICHEN ZONE 3

Crustose lichen Bacidia neosquamulosa on Poplar bark.

HAWKSWORTH and ROSE SCALE

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