In New Zealand, lichens are found on all types of land, from the coast to high-alpine rocks. There are thought to be over 2,000 lichen species, slightly more than the number of native seed plants (about 1,900). But it will be years before the exact number of lichens in New Zealand can be known, because many are too small to be seen easily, and too few lichenologists are searching for them.
Relatively few New Zealand lichens are endemic (meaning that they grow nowhere else) – less than 40% are unique to New Zealand, compared to 84% of the country's seed plants.
The aggressive lichen Xanthoparmelia scabrosa colonises the edges of asphalt roads and carparks in the wetter parts of New Zealand, forming blue-green rosettes. It also takes hold on roof tiles.
Living with pollution
Most lichens are killed by sulphur spewed from car exhausts, but Xanthoparmelia scabrosa makes lichen substances that react with the sulphur and render it harmless. This solution is so successful that in places the lichen blankets the entire road.
The trunks and branches of apple and plum trees are sometimes host to clumps of the harmless yellow-orange Teloschistes chrysophthalmus.
Byssoloma adspersum usually grows on rock, but also thrives on timber preserved with CCA (copper, chromium and arsenic), where it leads a charmed life free of competition from other lichens.
Coastal and lowland areas
The bright yellow-orange Xanthoria ligulata is a common crust-forming lichen of coastal rocks, but it is equally at home on gravestones and exposed slabs of concrete. In shade, its colour changes to a dull blue-grey. In full sunlight it produces an orange pigment that is thought to act as a protective sunscreen for its algal partner.
Placopsis parellina var. microphylla lives on coarse soil. It secretes a glue that binds together sand, gravel, and loose soil particles, and it stabilises riverbeds in Canterbury and Otago, where most plants are washed away during flash floods.
A number of fruticose lichens can be found on ground that has lost its natural cover, such as the banks of roads and tracks that have been cleared or where slips have occurred. Pixie cup lichens (some species of Cladonia) and Stereocaulon can often be found growing in thumb-high tufts at such sites.
Large foliose (leaf-like) lichens are commonly found on tree trunks. The largest are species of Pseudocyphellaria and Sticta, which can grow to the size of an A4 sheet of paper. Another large foliose lichen, Menegazzia pertransita, grows on the trunks of beech trees in wet Fiordland.
On the forest floor, Trapeliopsis congregans flourishes on decaying logs and stumps. Psoroma asperella settles on mosses, and the crustose Thelotrema novaezelandiae overruns liverworts.
New Zealand forests, like tropical rainforests, have a number of lichens that live on the uppersides of leaves.
Colours to dye for
New Zealand spinners who dye their wool prize the lichen Pseudocyphellaria coronata. Compared with brightly coloured synthetic dyes, lichen dyes, some of which are pleasantly fragrant, yield a wide range of subtle colours depending on what mordant is used.
Light penetrates shrublands, allowing crustose lichens such as Haematomma alpina and the fruticose Usnea species to thrive on the branches and stems of subalpine shrubs.
Subalpine bogs and exposed, damp peatlands have a characteristic lichen cover which is dominated by coral lichen (Cladia retipora) and similar looking fruticose species belonging to the genera Cladina and Cladonia.
Subalpine and alpine rocks and soils
Crustose and fruticose species abound in the mountains. If you tramp above the treeline anywhere in New Zealand, you will come across the rock lichen Rhizocarpon geographicum. Climatologists can track global warming by measuring how quickly this lichen invades rocks freshly exposed by melting glaciers.
Rust-coloured Placopsis lateritioides is also at home on alpine rocks, where it forms tough crusts.