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Word of the Week: Thallus

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Welcome to Word of the Week! Stay tuned for a new word each Friday to amp up your nature vocabulary!

Word of the week is Thallus [THAL-uh s] (botany noun): A plantlike vegetative body (as of algae, fungi, or mosses) that lacks differentiation into distinct parts (such as stems, leaves, and roots) and does not grow from and apical point.

This fun word comes from the Greek word “thallos”, meaning “a green shoot” or “twig.”

Historically, this word was more rooted in botany and less so in mycology, when used to describe algae, fungi, and other various bryophytes. However, since these are no longer classified as plants, the word “Thallus” is still used to describe the bodies of algae and fungi, but as a “plantlike” body rather than the body of a plant.

An organism to which the word “thallus” also applies to is Lichen! These incredible organisms consist of a symbiotic association between photosynthetic algae and fungi. They are also found worldwide, occurring in various environmental conditions!

The thallus of a Lichen can come in 4 main growths forms:

Foliose– leaflike, with flat sheets of tissue not tightly bound

Fruticose– free standing branching tubes

Crustose– crust-like, growing tight against the substrate

Squamulose– tightly clustered and slightly flattened pebble-like units

If you are interested in learning more about Lichens, you can register TODAY for the “High Park Lichens: Discover the ‘Corals’ of the Forest” workshop, led by research scientist in Lichenology, Dr. Troy McMullin. This workshop will take place on Saturday, February 22, 2020, 12:30PM-5PM.

Click here to register!