It Takes Two To Tango

From majestic rusty plains dotted with sunken Mars-like craters, to gaping fissures of vivid greens and purples, one wouldn’t expect to find such psychedelic sights here on Earth!

Whether you think they resemble the surfaces of alien planets or simply appreciate the exotic personality they bring to the natural world around us, our planet would not be the same without Lichens.

Better yet, lichens exist almost everywhere on Earth! – From eerie graveyards to rocky coastlines, from sweltering deserts to the frozen plains of Iceland, sooner or later you’re bound to discover the world of lichens at your very fingertips!

Exotic ‘lichen landscapes’ here on Earth. Source: Pixabay

But like the saying goes, it takes two to tango.

Lichens are no exception it would seem. Scientifically speaking, lichens are the product of not one, but two different organisms! – That is, they represent a harmonious, symbiotic partnership between an alga and a fungus.

Such a partnership typically involves a ‘green alga’ or ‘blue-green alga’ (cyanobacteria), such as Nostoc or Scytonema, living inside either an ‘Ascomycete’ or ‘Basidiomycete’ type fungus.

Like Shakespeare’s ‘star struck lovers’, this dynamic fungal-algal duo is almost inseparable, going to great lengths to grow together in the most unforgiving of places.

Nothing is off limits, with leaves, bark, rocks and even other lichens making for prime real-estate.

Many ‘daring’ lichen duos grow as epiphytes (on trees) with some even found dangling precariously from tree-branches.

Lichens growing over tree branches. Source: Pixabay.
Lichens growing on the tip of a giant boulder. Good thing they’re not afraid of heights! Source: Pixabay.

Like all good relationships, the secret to the longevity of this fruitful partnership lies simply in the fact that both parties mutually benefit from this alliance.

Whilst the photosynthetic alga or ‘photobiont’ supplies its fungal partner with energy-rich photosynthetic products such as carbohydrates (sugars), the fungal filaments ‘heroically shield’ the algae from the harsh dangers of the surrounding environment.

Naturally, with such a myriad of pairings possible between these algae and fungi, and with fungi able to pair with multiple algae, it is not surprising that so many different types of lichens exist!

Generally speaking, lichens are classified into one of four major growth forms:

  • Crustose Lichens = These lichens grow closely on the surface of the substrate, forming a ‘crust-like’ layer.

    An example of a ‘crustose lichen’. Source: Pixabay
  • Squamulose Lichens = These lichens form minuscule scales called ‘squamules‘ which overlap whilst others may resemble loose pebbles aggregated into compact clusters.

    A member of the genus Xanthoria, an example of a ‘squamulose lichen’. Source: Pixabay
  • Foliose Lichens = Resemble loose, flat sheets that are not tightly fixed to the substrate or ‘growth surface’.

    An example of a ‘foliose lichen’. Source: Pixabay
  • Frucitose Lichens = These lichens are proud to be different and really stand out from the crowd! They form upright, branching tubes that protrude from the substrate surface.

    ‘You only live once’ seems to be the motto of these daring ‘frucitose lichens’ (pictured below a ‘crustose lichen’). Source: Pixabay

But the real burning question is: How do lichens obtain their outstanding colours?”

For lichens of the standard ‘green’ variety, their colour typically arises from the chlorophyll pigments of the underlying algae located inside the fungal filaments.

On the other hand, some of the more ‘exotic’ lichens owe their appearance to a range of specialised chemical pigments.

For example:

  • ‘Groovy Orange’ and ‘Bright Yellow’ lichens contain a kaleidoscope of coloured chemical pigments including pulvinic acid, vulpinic acid, pinastric acid and leprapinic acid just to name a few! A study published in 1979 in the ‘Journal of Separation Science’ managed to successfully isolate the numerous acids found in yellow-series lichens.
  • Vibrant Red’ lichens owe their startling tinges of red to chemicals called ‘anthraquinones

A joint study published in ‘New Phytologist’, conducted in partnership with the Agricultural University of Norway, recently discovered that these additional pigments in lichens provide a degree of UV-protection, such as in the case of the common orange lichen, Xanthoria parietina.

Orange-series lichens such as those in the genus Xanthoria, get their brilliant colours from pigments such as pulvinic acid. Source: Pixabay
At the end of the day, lichens are certainly wondrous, composite organisms that bring vibrant splashes of colour wherever they go – so be sure to keep an eye out for them on your spring travels!

8 Responses to “It Takes Two To Tango”

  1. Evie Kielnhofer says:

    @Bree Thanks for the awesome feedback and glad you liked it 🙂 Go Lichens! 😀

  2. Bree Iredale says:

    How cool are lichens, great post. Factual, well-written and humorous … the trifecta!
    Love the colourful photos too! Thanks Evie

  3. Evie Kielnhofer says:

    @Kai Yee Thanks for your kind feedback and glad you liked the photos 🙂

  4. Kai Yee, Chan says:

    Interesting post. Thanks for the detailed information and lovely photos.

  5. Evie Kielnhofer says:

    @Rob Thanks for your kind feedback. I agree, Lichens sure have impressive habitats! 😮 As for the image, I uploaded it in high-resolution format in the ‘preview image’ setting in the blog menu (which seemed to come up better than dragging and scaling the image in the blog-editor).

  6. Rob Dabal says:

    They’re such tough units lichens. Crustose orange on granite boulders at the Prom are up there as my favourites. Filamentous frucitose in wet forests are also pretty impressive. Great visuals in your post and an enthusiastic rhythm to your writing. Nice work. How did you get the first image to scale up so well?

  7. Evie Kielnhofer says:

    @Sam, thanks for your feedback 🙂

  8. Sam Girvan says:

    Love a good lichen fact, thanks so much for this informative and emotive piece.