shields the sunny urban tree trunks
- Size
- Width: 5–15 cm
- Lifespan
- 10–50 years
- Diet
- Symbiotic partnership. Fungus provides structure. Alga provides food via photosynthesis. Requires clean air and good light.
- Habitat
- Grows on bark of trees, rocks, and occasionally old fence posts throughout New Zealand. Found from sea level to montane zone in open, sunny locations.
- Range
- Found throughout North and South Islands on bark of native and introduced trees. Most common in North Island and northern South Island. Also found worldwide.
- Endemism
- Native
- Main Threats
- None significant. One of most common lichens in New Zealand. Localised threats include air pollution, removal of old trees, and bark disturbance.
- Population
- Not Threatened. Common and widespread lichen in New Zealand. Particularly in North Island and northern South Island. Grows on bark and rocks.
- Conservation Status
- Not Threatened
- Human Risk
- harmless
- Handling Note
- foliose lichen, safe to handle
- Conservation Note
- Native lichen; not assessed by NZTCS as lichens are generally outside the scope of current threat classifications.
- Te Ao Māori
- No recorded Māori name distinguishes green shield lichen from other lichens. Lichens were generally called pūkohu or pukorokoro. Pale green colour would have been noticed. Looked like green of new leaves. Like moss on forest floor. No distinct name survives. Sometimes used as dye. Pale green pigment extracted to colour fibres. Though not as vibrant as others.
Flavoparmelia caperata looks like it is glowing. Its body is flat, leafy, and pale green. Distinctive yellowish-green or apple-green. Stands out against grey bark. Lobes are broad and rounded. Spreading across trunk like map of foreign country. Surface is smooth and shiny. Often covered in network of fine, white lines. It is the lichen of the pale light. Looks like catching sun even when sun is not there.
What makes it special is the colour. Green shield lichen is one of few lichens in New Zealand that is truly green. Most grey lichens have hint of green. This one is green. Pale, bright, almost luminous. Colour comes from alga living inside. Species of Trebouxia. Particularly efficient at capturing light. In shade, turns darker olive green. In sun, fades to pale yellow-green. Chameleon of green world. Changes with light.
Surface of lobes is smooth and shiny. Often with network of white, wavy lines. Margins are entire or slightly wavy. Not frilly like ragged parmelia. Underside is black. Covered in sparse mat of rhizines. Tiny, root-like structures anchoring it to bark. Under hand lens, white lines visible. Delicate network on green surface.
Biologically, it is a partnership. Fungus and alga living together. Fungus provides structure and protection. Alga provides food through photosynthesis. Particularly sensitive to air pollution. Less common in cities and industrial areas. In clean air, it thrives. Canary of the bark. Tells us whether air is healthy.
To find green shield lichen is to find pale green patch on bark. Flat, leafy, and bright. Living glow on tree. Run finger over surface. Feel smooth, shiny texture. Lichen of pale light. Looks sunlit even in shade. Proves that even in dark corners of forest, there is little bit of sun. It carries on regardless.