Identification of foliose lichens on trees

Key to foliose lichens on trees or wood (excluding rare species)

1. Lichen is bright yellow in colour – Go to 2
Lichen is not bright yellow in colour – Go to 5

2. Lichen with lobes more or less pressed flat on trees – Go to 3
Lichen with lobes or branches spreading away from surface of tree – Go to 4

3. Outer lobes larger than the central apothecia – Xanthoria parietina
All lobes smaller than the numerous and widespread apothecia – X.polycarpa

4. Lichen turns crimson when sodium hydroxide applied – Xanthoria candelaria
Lichen turns brown when sodium hydroxide applied – Candelaria concolor

5 Apothecia of lichen are flat discs or there are none – Go to 6
Apothecia of lichen are at the top of stalks (podetia) – Go to 32 (Cladonia)

6. Lichen with lobes or branches spreading away from surface of tree – Go to 7
Lichen with lobes more or less pressed flat on trees – Go to 15

7. Lichen bush like, often pendulous and with many thin, wiry branches – Go to 8
Lichen with strap like branches or erect lobes and not pendulous – Go to 10
The lichen has erect, sometimes crisped, lobes (not strap-like) – Go to 12

8. Lichen mostly reddish-brown in colour – Usnea rubicunda
Lichen is grey in colour with larger ciliate apothecia looking like flowers – U.florida
Lichen is grey in colour without large ciliate apothecia – Go to 9a

9a. Some of the branches of the lichen are inflated (like sausages) – U.articulata
The branches of the lichen are all thin but their central cores are pink – U.ceratina
The branches of the lichen are all thin but their central cores are white – Go to 9b.

9b. Side branches of lichen constricted at junction of main branch and the holdfast is pale grey – Usnea cornuta
Side branches not constricted at junction of main branch and the holdfast is dark blackish – Usnea subfloridana

10. The underside of the strap-like branches is pure white – Evernia prunastri
The underside of the strap-like branches is black – Pseudevernia furfuracea
Both sides of the strap-like branches are the same grey colour – Go to 11

11. The lichen has large numbers of whitish apothecia – Go to 11a
The lichen has no apothecia but have pale soralia on branches instead – Go to 11b

11a. All of the apothecia are apical i.e. at the end of branches – Ramalina fastigiata
The apothecia are marginal, laminal and apical – Ramalina fraxinea

11b. The lichen has very slender branches with small disc-like soralia along the margins only – Ramalina farinacea
The lichen is slightly branched with broad, wrinkled lobes and the soralia are confined within the inflated lobe tips – Ramalina canariensis
The lichen is very irregularly wide or narrow lobed with laminal and marginal soralia – Ramalina lacera

12. The lobes of the lichen have conspicuous marginal cilia – Go to 13
The lobes of the lichen have no marginal cilia – Go to 14

13. The tips of the lobes are hooded hiding the soredia below– Physcia adscendens
The tips of the lobes are rolled back to fully expose the soredia – P.tenella

14. The lichen is crisped and cauliflower-like, the fronds are pale brown below – Platismatia glauca
. The lichen has hollow, branching lobes that are all dark grey below – Go to 14a

14a. The lichen has tubular lobes with soredia at the tip only – Hypogymnia tubulosa
. The lichen has some flattened lobes and soredia below as well as at the tips – Hypogymnia physodes

15 The lichen has numerous disc-like apothecia – Go to 15a
The lichen has no or very few disc-like apothecia – Go to 16

15a The lichen is pale grey with large black apothecia and the lobe tips are not pruinose – Physcia aipolia
The lichen is pale brownish-grey with brown apothecia and distinctly pruinose tips to the lobes – Physconia distorta

16 The lichen is very pale grey in colour, almost white – Go to 17
The lichen is some shade of grey but without brown or green tints – Go to 18
The lichen is pale greenish-grey or darker with brown or green tints – Go to 25

17 The lichen has neat convex lobes descending at tips and is very pruinose
– Diploica canescens
The lichen has flat or concave lobes that are not pruinose – Go to 17a

17a The lichen is a flat rosette with bluish-grey circular soralia – Physcia caesia
The lichen has ascending crispy lobes with marginal soredia – Physcia tribacia

18 The lichen is partly covered with numerous isidia (rod-like projections) – Go to 19
The lichen is partly covered with numerous soredia (powdery granules) – Go to 20
(Note: There are some rare species with neither isidia or soredia)

19 The lichen has white pseudocyphellae and no marginal cilia – Parmelia saxatilis
The lichen has marginal cilia but no pseodocyphellae – Parmotrema crinita
The lichen has isidia but no marginal cilia or pseudocyphellae – Go to 19a

19a The lichen has scattered black isidia in centre of lobes - Parmelina pastillifera
The lichen has crowded brown isidia in centre of lobes – Parmelina tiliacea

20 The inner part of the lichen turns pink or red when bleach is applied to it – Go to 21
The inner part of the lichen turns bright yellow when bleach is applied to it (and it has small lobes about 1mm across) - Parmeliopsis ambigua
The inner part of the lichen does not turn red or bright yellow when bleach is applied – Go to 23

21 The lobes of the lichen are not pale dotted and they are turned down at the tips – Hypotrachina revoluta
The lobes of the lichen are pale dotted and they ascend at the tips – Go to 22

22 The soralia of the lichen turn slightly pinkish-red when bleach applied and the underside is not black in the centre – Punctelia subreducta
The soralia of the lichen turn strongly orange-blood red when bleach applied and the under surface of the lichen is black in the centre – Punctelia borreri

23 The lichen is silvery-grey and has large, smooth broad lobes – Rimelia reticulata
The does not have particularly large lobes and is not silvery – Go to 24

24 The surface of the lobes are finely pale dotted all over – Punctelia reddenda
The surface of the lobes have raised lines of pseudocyphellae – Parmelia sulcata
The surfaces of the lobes are smooth but the edges are very crenulated with numerous soredia – Parmotrema perlata



25 The lichen is a pale greenish-grey (maybe darker green when wet) – Go to 26
The lichen is a distinctive olive-brown or greenish-brass colour – Go to 27
The lichen is deep greyish-green, brown or brownish-grey – Go to 28

26 The lichen has coarse soredia and these turn an unchanging yellow when bleach is applied to them – Flavoparmelia caperata
The lichen has fine soredia and these turn yellow and then red when bleach is applied to them – Flavoparmelia soredians

27 The lobes are glossy and the isidia are minutely branched – Melanelia glabratula
The lobes are dull and the isidia are granulate (not coralloid) – M.subaurifera

28 The lichen is a distinct somewhat shiny dark blue-green with lobes up to 15mm across – Pleurosticta acetabulum
The lichen is variously coloured and the lobes are small (up to 2mm wide) – Go to 29

29 The lobes are very narrow (0.5mm wide) and there are abundant greenish soredia – Hyperphyscia adglutinata
The lobes are narrow (1 to 2mm wide) and the soredia are greyish – Go to 30

30 The lower surface of the lichen is black and the soralia are black dotted – Phaeophyscia orbicularis
The lower surface of the lichen is pale and soralia are not black dotted (also the lichen is distinctly paler towards the edge) – Go to 31

31 The lichen is a distinctive dark greenish colour with tufted, dark rhizines underneath – Physconia perisidiosa
The lichen is dark grey with simple, pale rhizines underneath – P.grisea

32 The lichen has bright red apothecia on grey stalks (podetia) – Cladonia macilenta
The podetia of the lichen is goblet-shaped (cup on a stalk) – C.pyxidata
The podetia of the lichen simple, tubular and tapering – C.coniocraea
The podetia of the lichen is branched and scaly – Go to 33
(On very rotten wood some different species of Cladonia may occur)

33 Brown apothecia present at the top of the podetia – Cladonia ramulosa
Brown apothecia completely absent and potedia very scaly – C.squamosa

Glossary:

Apical: At the tip of the lobes
Apothecia: Disc-shaped fruiting body from which spores are produced
Cilia: Hair-like structures, usually on the margins of the lobes
Crenulate: A regularly notched margin
Foliose: Leaf-like or lobed
Isidia: A tiny, usually rod-like, detachable extension on thallus. This structure contains photosynthesising algae.
Laminal: Something on the surface of the lobes.
Potedia: The stalk of the fruiting body of lichen
Pruinose: A fine, white powdering as if sprinkled with flour
Pseudocyphellae: Dot or line on the lobe surface where the outer skin is absent
Rhizine: Root-like outgrowth of fungal filaments underneath the lichen
Soralia: Reproductive structure containing soredia
Soredia: Small powdery structures containing algal and fungal cells
Thallus: The main body of lichen, containing algal and fungal cells

......... .... Phil Budd 31/01/07








List of the best trees for lichens in Hampshire:

Acer sp. (Maples or Sycamore)
Catalpa bignonioides (Indian Bean Tree)
Crataegus sp. (Hawthorn)
Fagus sylvatica (Beech)
Fraxinus excelsior (Ash)
Juglans regia (Walnut)
Liriodendron tulipifera (Tulip Tree)
Malus sp. (Apple)
Morus nigra (Black Mulberry)
Populus nigra agg. (Black/Lombardy Poplar)
Prunus spinosa (Blackthorn)
Rhamnus cathartica (Common Buckthorn)
Quercus robur (English Oak)
Salix sp. (Willows and Sallows)
Sambucus nigra (Elder)
Tilia sp. (Limes)