As the leaves fall off the deciduous trees and shrubs and the flowers decide it is too late in the season to burst forth, the lichen that we grow so well slowly becomes more obvious. Through much of the growing season the lichen is but a second class citizen within the garden realm, at this time of year though, it begins its move into the upper tiers.
At Larnach Castle we do many odd and difficult to grow plants particularly well, such as blue poppies and Veratrum nigrum.
Lichen is another ‘plant’ that we also do extremely well. Those of you who are observant may have noticed the quotation marks around the word plant and they do exist for a reason, that is, they are not just typing errors. So what are lichens and why do we do them so well?
What are lichens?
Moons ago, when I was studying botany they were sort of considered plants but things have come a long way since then (which of course has nothing to do with my present age). Lichen is at least two completely different organisms living in a commune, the structure created by one of them.
The outer surface we see is a fungus; the different fungi involved creating the multitude of forms and colours that lichen can be. Protected within the walls are algae or cyanobacteria, both of which undertake photosynthesis (and yeast are the new kid on the block, recently discovered to be a part of this microscopic community).
It is these microscopic little organisms that make the food, the sugars to sustain them both, whilst the fungi provide the protective home and grab water and nutrients primarily from the. Such a relationship is said to be symbiotic, even mutually symbiotic, because both parties benefit.
Like everything in life this could also be debated; is the fungi just a scrounger, taking food but giving little in return, but a home to live in …. ahh the dilemma.
How long this association has existed for is still under debate, as with so much when we are looking so far back in time. It was thought that this association developed around about when plants first came onto the land but in 2005 a 600 million year old fossil was found in South China – the mind boggles as to how such a fossil came to light and the likelihood of that once living organism showing itself to the light of day millennia plus later.
Such old old organisms reminds us that we are but a blip on Earth’s timeline.
Lichen are not parasites, taking food or nutrients off the plants they can attach to, the plant is but a surface for the lichen to adhere to and grow and, are considered just as suitable as a building, a rock or even asphalt for that matter.
They are incredible
They exist from the coldest to the hottest places, from sea level to the tops of mountains. In the harshest sites they may grow only 2 – 20mm per century. The oldest are thought to be over 5000 years old, ancient beings.
There are those that reindeer feed on and those that humans have used for millennia. Early Maori used them for sanitary pads and nappies and took advantage of their antiseptic properties. It provides the colour for Harris tweeds, is a fixative for perfumes, sunscreens... over 700 substance have been extracted some showing anti-cancer and antifungal properties. What is more they survived the chills and vacuum of space for two weeks with no detrimental effects.
They are a sign of clean air and interestingly the area surrounding an aluminium smelter in New Plymouth, years ago, was devoid of them and the council used it as a reason for them to clean up their act. Once they had done this, the lichen returned within a couple of years.
Why do we do them so well?
Firstly, New Zealand as a whole is a lichen haven, we have 2000 of the 20,000 species found worldwide (1). A whopping 10% when we only have 1.8% of the land area (1). To go one step further Dr David Galloway, a world renowned Dunedin lichenologist, said that little ol’ Dunedin was the most lichen rich city in the world, in terms of species diversity!
As for us up here it is all about our delightful maritime climate; our fog. Lichen has an amazing capability of dehydrating, shutting down ostensibly, when conditions become dry (organisms, like plants, that undertake photosynthesis, need water as an ingredient to make food). Conversely though they can rehydrate extremely quickly, hence taking advantage of any suitable situation to grow.
We have the moisture, we have the fog and hence lichen that resides within our bounds loves it!!!
Next time you look at these beautiful small communes, think of how extraordinary they are – great things come in small packages!
We are lucky to have the perfect home for them here at Larnach Castle.
2011 NZ geographic May/June issue
- The guarding lion beside the steps at the Castle covered in lichen and moss.
- Rockery – A Lilliputian world of lichen and moss
- Posts – Fifteen years of lichen growth on the posts in the South Seas garden
- Post – Lichen growing on a post in the South Seas garden
- Rock – Lichen imitating plate tectonics on a rock