Bryoria fuscescens (Gyeln.) Brodo & D. Hawksw. — Overview

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 Thallus: pendent (to prostrate in some morphotypes of var. positiva), relatively lax, usually 5-15 (-30) cm long, moderately branched; branching: isotomic or anisotomic at the base, often becoming anisotomic toward the apices, frequent from the base; axils: acute (to obtuse, but generally not broadly rounded); branches: terete, to sometimes partly flattened or twisted and occasionally foveolate (in var. positiva), somewhat unevenly (to evenly) thickened, (0.2-) 0.3-0.4 (-0.6) mm in diam. near its base, but main or secondary branches often 0.1 mm diam.; surface: pale to medium brown or somewhat grayish or olivaceous, to blackish, usually much paler at the base than at the apices, often with black fragmentation regions, often dull but sometimes quite shiny; pseudocyphellae: lacking; lateral, spinulose branches sometimes present but inconspicuous; true lateral spinules: lacking; soralia: sparse or abundant, fissural (sometimes resembling pseudocyphellae when young) or sometimes also tuberculate, often strongly convex at maturity, sometimes becoming spinulose, usually white; Spot tests: cortex and medulla K-, C-, KC-, UV-, P- or P+ red (v. positiva); soralia: P+ red-orange; Secondary metabolites: fumarprotocetraric and protocetraric acids (and accessory chloroatranorin in specimens from eastern North America).; Substrate and ecology: on bark, mostly of conifers in dry and open forests (Pinus ponderosa and Pseudotsuga forests); var. positiva has also been reported from lignum, and from rocks in highly exposed sites; World distribution: circumpolar and boreal and in the East African mountains; Sonoran distribution: Arizona, c. 2875-3400 m, in pine and spruce-fir forest.; Notes: It is characterized mainly by P+ red-orange soralia, mostly V-shaped axils, and typically grayish brown and often dull surface, which is usually paler at the base. The thallus is often pendulous but rarely forms long, thick beards. It is an extremely variable species and is treated here in a very broad sense. Most material from the Sonoran region tends to have much finer branches than previously described (Brodo and Hawksworth 1977), and is therefore often very difficult to distinguish from the frequently intermixed B. lanestris, The only other Bryoria known from North America that has P+ red soralia and very narrow branches is B. subcana, which has a pale gray to brown, short thallus (up to 5 cm long) and is found in maritime areas well north of the Sonoran region. Some collections included here under B. fuscescens appear to be mixtures of short, very pale thalli with ± longer and/or darker ones. The palest (almost whitish) ones may represent basal or dying parts, but have a rather different appearance. Coarser, darker, or shorter forms of B. fuscescens from exposed habitats can be similar to B. chalybeiformis, that primarily occurs on rock or soil. Bryoria fuscescens is usually more grayish brown, and have tuberculate soralia. 


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© Lichen Unlimited: Arizona State University, Tempe.

Source: Lichen Flora of the Greater Sonoran Desert Region

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