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Montana Field Guide

Montana Field Guides

A Lichen - Rhizoplaca haydenii
Other Names:  Lecanora haydenii

Species of Concern

Global Rank: G2G3
State Rank: S1S2
* (see State Rank Reason below)

Agency Status
MNPS Threat Rank:

External Links

State Rank Reason (see State Rank above)
Known from a few locations in south-central to southeastern Montana. This species is also likely to be found in appropriate habitats in southwestern Montana. Both subspecies are found in Montana: R. haydenii ssp. haydenii and R. haydenii ssp arbuscular.
General Description
Thallus of discrete lobes or squamules that are fruticose or strongly 3-dimensional foliose in form; Thallus pale greenish to yellow green; abundant marginal whitish nodules or whitish markings present on thallus; lobes spreading and erect, flat to round, or strongly rolled under, distinctly dorsiventral or not; rhizines are lacking; apothecia not known (McCune and Rosentreter 2007). Chemistry: Cortex with usnic acid and spot tests are often positive; Medulla K- and P- (McCune and Rosentreter 2007).

Species Range

Summary of Observations Submitted for Montana
Number of Observations: 8

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Found on cold dry steppe to alpine habitats. Thallus loosely attached or free on windswept, sparsely vegetated, rocky calcareous soils.

Soil crust lichen.

Threats or Limiting Factors
None identified.

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Citation for data on this website:
A Lichen — Rhizoplaca haydenii.  Montana Field Guide.  .  Retrieved on , from