Bryoria fuscescens (Gyelnik) Brodo & D. Hawksw.
Pale-footed Horsehair Lichen
Alectoria fuscescens, Bryopogon fuscescens
Basis for Listing
Bryoria fuscescens (pale-footed horsehair) is a widespread species in North America. It occurs throughout the western mountains (from Arizona through Alaska) and across the arctic and boreal forest into New England. This species reaches the southern limit of its mid-continental range in Minnesota and appears to be infrequent in the northern portion of the state. In all, B. fuscescens has been collected fewer than 20 times in Minnesota; the majority of occurrences have been documented from Cook and Lake counties, and single populations have been recorded from Itasca, Cass, and Hubbard counties. Bryoria fuscescens was listed as a state special concern species in 2013.
Bryoria fuscescens is a fruticose (shrub-like) species, with a brown colored thallus (lichen body). In Minnesota, there are seven species of Bryoria, all of which are similar in outward appearance (Wetmore 2005). Bryoria fuscescens can be very difficult to distinguish from the other six species of Bryoria without the aid of chemical spot tests (chemical tests used in lichenology).
In general, B. fuscescens can be separated from the other species of Bryoria in Minnesota by the following characteristics: Bryoria fuscescens has a pendent or draping rather than a tufted or bushy growth habit. The thallus of B. fuscescens is generally some shade of brown rather than gray and usually has soralia (localized patches of soredia or asexual reproductive structures that contain both fungal and algal partners) present but does not have pseudocyphellae (localized regions of thinness in the cortex or outer surface of the lichen). Additionally, the cortex of B. fuscescens turns red when exposed to paraphenylenediamine (PPD) and does not react to potassium hydroxide (KOH) in chemical spot tests (Wetmore 2005). Although a chemical spot test may not be necessary to identify B. fuscescens, it can aid in the determination of "intermediate" specimens.
In Minnesota, B. fuscescens is restricted to the Northern Superior Uplands and Minnesota Drift and Lake Plains sections of the Laurentian Mixed Forest Province. Bryoria fuscescens does not seem to be habitat specific in the state; it has been recorded from forested rich peatland, fire-dependent forest, and acid peatland systems. Minnesota populations of B. fuscescens have been recorded from the bark of various conifers as well as large or gnarled Betula papyrifera (paper birch) and Betula cordifolia (heart-leaf birch). A series of recent collections of this species were made from northern dry cliff communities above large lakes in the Border Lakes Subsection of the Laurentian Mixed Forest Province. These collections likely represent B. fuscescens var. positiva, a variety that occurs in highly exposed environments and is known from Isle Royale, Michigan. Although the habitat seems to vary greatly, it is likely that all sites with B. fuscescens have consistently high humidity.
Biology / Life History
Apothecia (disk-shaped fruiting bodies) are unknown in North America specimens of B. fuscescens (Brodo and Hawksworth 1977), so reproduction is strictly asexual and depends on the dispersal of soredia and thallus fragments. Soredia are reproductive structures that contain both fungal and algal partners and can be dispersed over short distances. Soredia can be dispersed by wind, water, animal, or insect. If the soredia are deposited in a favorable habitat, a new lichen thallus can grow from them.
Conservation / Management
Loss of habitat is the primary threat to B. fuscescens in Minnesota. Since the substrate for B. fuscescens is tree bark, the most prominent agents of habitat alteration or destruction would be the removal of trees and environmental changes such as climate change. Any alterations that disrupt the humidity of B. fuscescens’ environment would likely have a negative impact on populations of this lichen.
Best Time to Search
Bryoria fuscescens can be observed year-round, whenever lichens are not covered by snow or ice.
References and Additional Information
Brodo, I. M., and D. L. Hawksworth. 1977. Alectoria and allied genera in North America. Opera Botanica 42:1-164.
Minnesota Department of Natural Resources. 2003. Field guide to the native plant communities of Minnesota: the Laurentian mixed forest province. Ecological Land Classification Program, Minnesota County Biological Survey, and Natural Heritage and Nongame Research Program. Minnesota Department of Natural Resources, St. Paul, Minnesota. 352 pp.
Wetmore, C. M. 1981 (revised 2005). Keys to the Lichens of Minnesota. Department of Plant Biology, University of Minnesota, St. Paul, Minnesota. 92 pp.