(tumbleweed lichen)
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Photo of Masonhalea richardsonii by Taylor Keegan
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One of the showiest lichens in Alaska, tumbleweed lichen is found roaming loose in the tundra. When dry, the greyish-green tumbleweed lichen curls up into a loose ball, allowing it to be carried by the wind. When damp, the now reddish-brown
thallus spreads out, gripping onto other tundra plants. In swales or depressions in the alpine, you can often find hundreds of individuals of this species piled into a heap. The
thallus is
foliose, thin and dichotomously branching, the branches 2-5 mm wide.
Thalli grow 4-15 cm long (when lain flat), dark brown on the upper surface (turning brownish-green when wet), with long white patches on the underside. The
apothecia are very rarely present, when found they are round , the same color as the
thallus and produced at the tips of the lobes. No other lichen in Denali has a similar tumbleweed habit.
Tumbleweed lichen mainly spreads vegetatively, by breaking into fragments and regrowing. Sexual reproduction via
apothecia has been seen, but is rare.
Amphi-Beringian, found in eastern Siberia, Alaska and northern Canada.