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Leptogium minutissimum (Flörke) Fr.
Family: Collemataceae
[Collema minutissimum Flörke,  more]
Leptogium minutissimum image
Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus to 2 cm broad, of numerous spreading to commonly erect and often imbricate lobes, the lobes to 2 mm broad; margins entire to irregularly lobulate, the surface smooth, occasionally with minute lobules, lead-gray to brown; underside with tufts of hair; thallus paraplectenchymatous throughout, algae in chains throughout the thallus; hairs 2-3 μ in diameter from lower cortex. Apothecia sometimes abundant, sessile, to 1.5 mm broad; disk concave to flat, brown, red-brown, or dark chocolate brown; thalloid exciple entire, of same color as thallus or darker; proper exciple euparaplectenchymatous, about 10 ¡x broad but unclear; subhymenium hyaline to yellowish; hymenium 105-200 μ, hyaline, with thin yellow epithecium; paraphyses unbranched, 1-2 μ, slightly thicker at apices; asci cylindrico-clavate, 90-180 x 12-20 μ; spores uniseriate to irregular, ellipsoid with rounded tips, 3-5 septate transversely, 1-septate longitudinally, 21-35 x 7-14 μ.

This species grows on soil. It is circumpolar arctic to temperate, in North America ranging south to California, Colorado and West Virginia.