British Soldier Lichens

I was walking by the Crossroads Pond about a month ago when I spotted these lichens growing on top of an old post. It looked like a miniature world with a little tree surrounded by a bed of lichens and moss. I had seen this common species of lichen many times before. Here is a close-up.

These are called British soldier lichens because of the red caps on some of the branches. Some sources say the name comes from the red caps worn by british soldiers, but if so, this is a misnomer. British soldiers wore red coats, not caps. Nevertheless, the red is the source of the name.

As we all know, lichens are a symbiotic relationship between a fungus and a photosynthetic microorganism, either cyanobacteria or green algae. In this species, it is a green alga. The alga finds a protected home within the hyphae of the fungus. The fungus obtains nutrients from the photosynthesis by the alga. Although neither the fungus nor the alga survives as well on its own, the fungus appears to obtain more nutrient benefit from the alga than does the alga from the fungus. As lichenologist Trevor Goward put it “Lichens are fungi that have discovered agriculture”.

The red structures at the tips of the branches are fruiting bodies or ascocarps, a result of sexual reproduction. Lichens most commonly reproduce asexually by breaking off of pieces containing both fungal mycelium as well as the alga. This has the advantage of being sure that both components of the symbiotic relationship are present at the new growth site. Sexual reproduction in the lichen occurs only in the fungal component. For a discussion of sexual reproduction in fungi click here. After genetic combination, the fruiting body (the red structure) forms and contains the fungal spores which may be released and dispersed by the wind. In order to produce a new lichen, the spores must germinate and grow in the same location as the appropriate alga, which can only occur by chance. This may be a less efficient means of dispersal than asexual production, but allows for genetic variation of the organism which is important for adapting to a changing world.

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