A guide to lichens on twigs

Glossary

alga(e) - in lichens, single-celled or filamentous green organisms that contain chloroplasts.

apothecia- spore-producing fruiting bodies of the fungal partner.

asexual reproduction - reproduction without sex by producing vegetative propagules, isidia or soredia.

chloroplast - is an organelle in green plants that uses the sun's energy to turn carbon dioxide into carbohydrates.

cilia - whisker-like projections from the margin of a foliose lichen.

crustose lichens - crust-like lichens that grow directly on or under the bark surface and cannot be removed without cutting the bark.

foliose lichens - leaf-like lichens with spreading to upright flattened lobes that are attached to the twig from the lower surface of each lobe.

fruits - lichens reproduce sexually from spores produced in fruiting bodies (apothecia) by the fungal partner. Fruits may be rounded and jam-tart like with a distinct margin the same colour as the thallus (far left), or like wine-gums with margins and center the same colour (center left), or elongated fruits in wavy to star shapes (center right), or fruits may be enclosed in pot, volcano or wart-like bodies with a hole for spore release (far right).

fruticose lichens - branched, shrub-like lichens that are attached to the twig by a single sucker-like holdfast.

fungus (fungi) - spore-producing organism without chlorophyll.

isidia - darker (than thallus) finger- to knob-like propagules.

moss(es) - green spore-bearing plants with leaves.

rhizines - root-like attachments from the lower surface of a foliose lichen. They may be simple (left), branched (centre) or bottle brush like (right).

soredia - paler (than thallus) powdery to granular propagules containing algal and fungal partners. Often occurring in specialised bodies called soralia (far left), on the lobe margins or ends (center left), on the upper surface in cracks (center right), or as dots (far right).

sorediate - with soredia.

spores - produced in fruiting bodies following sexual reproduction.

sterile - without fruiting bodies.

thallus - the lichen body.

Key to symbols

- indicates lichen species found in undisturbed and unpolluted areas where little has changed over time and where nature conservation may be important.

- indicates lichen species that are stimulated by increased nitrogen from intensive farming.

- indicates lichen species that are tolerant of acid rain from industrial and traffic emissions.

+ red/orange - indicates lichen species whose identification in the field can be confirmed by a spot test with bleach (see Using the guide).

- indicates microscopic features where a magnifying glass or hand lens must be used (see Using the guide).