I'd like to take this moment to confess my doting admiration for one of the simplest symbionts of all that exist on this lovely planet, the lowly but enduring lichens. Here on the dry Kansas prairie, I had almost forgotten the existence of these composite organisms until I happened on this healthy lichen plantation growing on the north side of the trunk of my young pecan tree. I do see lichens everyday in Kansas, manifested as ugly black scale on the limestone of the K-State campus buildings, but there is hardly anything to admire about dirty-looking limestone, so please excuse me if I've almost forgotten their more attractive cousins.
Lichens are partnerships of a fungus (the mycobiont) and an algae or cyanobacterium (the photobiont), that grow in some of the most inhospitable environments on Earth; bare rock, arctic tundra, and hot deserts. They're so tough that they can survive the vacuum and cosmic radiation of space and they will grow in a Martian simulator, suggesting that they will be of use someday as Mankind terraforms Mars. The fungus surrounds and sometimes penetrates the algal cells, protecting them from dry environments, while the algae are photosynthetic and provide energy and food to the partner. Cyanobacteria in the cyanolichens serve to fix nitrogen, sharing this important building block with their mutual fungus partner.
I should also confess that ProfessorRoush was (and is) one of those weird kids who was often found reading a random volume of a paper and ink concoction formerly known as an encyclopedia. My parents once owned an entire set of a 1964 edition, purchased by my mother from one of the sweet, clean, predatory college students who used to travel the country each summer taking money off of doting mothers of budding science and space travel nerds. Today, I frequently satisfy that urge to explore new worlds with a Wikipedia search, clicking from subject to subject in a seemingly endless journey. Lichens are certainly a fertile search muse for some fascinating hours of Wiki-diving. For example, I learned that Swiss scientist Simon Schwendener was the first to discover the symbiotic nature of lichens (in the year 1867). I also found out that lichens reproduce by the dispersal of diaspores (which contain both algal and fungal cells), and that there are three types of diaspores; soredia, isidia, and what are essentially just dry lichen fragments that blow around in the wind. If by chance you are not yet fascinated by these organisms, it might thrill you to know that there are experts in Lichenometry, experts who can determine the age of exposed surfaces based on the size of lichen thalli and who regularly measure glacial retreat in global warming studies. Wouldn't we all love to have that job so that we could easily pick up girls at a cocktail party? One more factoid for the medical marijuana crowd; certain species of lichens contain olivetol, a substance also found in the cannabis plant where it is a precursor for the production of THC. Lichen brownies, anyone?
I'll stop here with the satisfaction that I know more today than I did yesterday. Even though it's possible that I could have continued my existence without ever learning more about lichens, it is probable that we owe lichens our very lives for their actions of converting rock to soil, thus allowing plant life to flourish on Earth, and ultimately enriching the lives of gardeners. Oh, and by the way, lichens don't hurt your trees.
Try to say "Swiss scientist Simon Schwendener searched soredia in the Seven Seas" three times fast.