“Vagabond Lichen”: {Aspicilia/Agrestia hispida}

  Agrestia hispida (aka Aspicilia hispida or  “Vagabond Lichen”)

Location Summary

Substrate: On calcareous soil & pebbles in dry, open prairies, at first attached but soon breaking free & becoming vagrant. Also on dry steppes.

Range: East Oregon to eatern Montana & northern Great Plains all the way south to Utah

Identification Characteristics

Description: Thallus fruticose, branching irregular to dichotomous, somewhat compact, branches short to elongate, tapered, often delicate. Branches with tangled clumps of terete branches, not tipped with conspicuous pseudocyphellae (which are instead scattered, abundant, & conspicuous). Thallus forming tiny, dull olive-green to blue-green, shrubby clumps up to 3 cm across; branches irregularly divided, terete, 0.5-1 mm in deameter, somewhat flattened in the oldest parts, with conspicuous white, depressed pseudocyphellae, 0.1-0.35 mm in diameter, dotting the branches; medulla white, dense. Photobiont green. Apothecia like those of Aspicilia contorta but rare.

Chemistry: Medulla PD-, K-, KC-, C- (no lichen substances).

Lookalikes: This is a fruticose species within the mostly crustose genus Aspicilia. Some lichenologists classify it within its own genus, Agrestia, & others regard it simply as a vagrant, fruticose form of A. calcarea. Aspicilia fruticulosa, a rarer member of this group, has white pseudocyphellae only on the branch tips, & the tips are blunt rather than pointed. Vagrant species of Rhizoplaca & Xanthoparmelia are yellow-green (containing usnic acid in the cortex) & usually have flattened lobes, although a form of Rhizoplaca haydenii can have terete, blunt-tipped branches.

Bibliography: Macrolichens of the Pacific Northwest, McCune & GeiserLichens of North America, Brodo, Sharnoff, & Sharnoff

Database Entry:  Distance Everheart 12-26-13

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