So I talk about apothecia a lot, but what exactly are apothecia? They are the fruiting bodies of the fungal constituent of lichens. They produce spores in internal sac-like structures called asci (singular ascus), and are typically cup, disc, or dome shaped. B. arceutina here has pale brown to brown-black apothecia which have a concolorous margin (the ridge surrounding the disk) and a flat disc when young, but become for bulbous and dome-shaped with age, often losing the marginal edge. Here is a cross section of a B. arceutina apothecium:
See all those little tube-y structures near the top? Those are the asci, and they are full of long, linear spores that look like this:
Spores like this aren't typical for all lichens, but are for lichens in the Bacidia genus.
I love them. So strange. These spores are sexually produced and ONLY contain the genetic material for the fungal constituent of the lichen, and not the photobiont constituent. So these microscopic spores, when dispersed, have to form a partnership with a Chlorphycea algae (one of my faves, TBH) if it wants to grow and thrive. So good luck out there, you tiny, wormy B. arceutina spores! I hope you can find purchase and partnership on the nutrient-rich, basic bark of trees and shrubs you prefer.
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