Montana Field Guide

GROWTH FORM: Foliose

THALLUS: Medium to large, usually 2-10 cm broad. Lobes broad, rounded, usually 1-5 cm wide. Upper surface yellowish-tinged, pale green to olive gray (dry), dark gray (wet), weakly ridged or undulating. Upper cortex often scabrous near the lobe tips, but lacking tiny hairs. Lower surface smooth or rugose, not distinctly veined, and with dense, fine, and short hairs (tomentose) interrupted by bare patches. Tomentum present throughout lower surface, often blackening. Rhizines usually abundant in cluster, to 3 mm long. Sources: Thomson 1984; McCune and Geiser 2023

PHOTOBIONT: Cyanobacterial. Layer appears dark-colored. Sources: McCune and Geiser 2023

REPRODUCTIVE TYPES: Sorediate. Apothecia rare. Sources: McCune and Geiser 2023

CHEMICAL REACTIONS: Spot tests often weak. Cortex KC+ yellow; medulla K+ yellow to orange, P+ orange (rarely P-), C-, KC+ red. Sources: McCune and Geiser 2023

TAXONOMY & NOMENCLATURE
Lobaria scrobiculata was initially recognized and described as Lichen scobiculatus by Giovanni Antonio Scopoli (latinized as Johannes Antonius Scopolius; 1723-1788), a professor of chemistry and botany in Italy (Yoshimura and Isoviita 1969; Wikipedia 2025a). In 1772, G.A. Scopoli took the specific epithet of scrobiculatus from a phrase used by Dillenius who also drew the lichen. Yoshimura and Isoviita (1969) researched the process to determine a standard name and authorship (typification) for Lobaria scrobiculata. They provide the evidence for using Dillenius’ drawing from 1741 which is based on a 1781 herbarium specimen housed at Oxford University (OXF) to serve as the lectotype because the Type specimen has never been found and is assumed lost due to housefire or shipwreck (Yoshimura and Isoviita 1969). They determined the nomenclature should be Lobaria scrobiculata (Scop.) DC.

The common name “lung wort” refers to their physical shape which resembles the lungs of a human being (Wikipedia 2025b).

Indigenous Yup’ik people in Alaska may call Lobaria scrobiculata Qelquaq (Brodo et al. 2001).

Montana has six Lobaria species, of which all but one is categized as a state Species of Concern. They are distinguished by the following characteristics:

Lobaria scrobiculata - Textured Lungwort, SOC
* Growth Form: Large foliose.
* Upper Surface: Yellowish-tinged pale green to olive (dry). Weakly reticulate-ridged or undulating
* Reproduction: Sorediate. Apothecia rare.
* Photobiont: Cyanobacterial. No internal cephalodia.
* Lower Surface: Coarsely mottled in color. Densely tomentose with bare patches and lacking small, white spots (pseudocyphellae).
* Chemistry: Medulla K+ yellow to orange, KC+ red
* Note: Closest look-alike to L. hallii, especially when wet.

Lobaria amplissima - Large Lungwort, SOC
* Growth Form: Minutely fruticose and erect. Tiny.
* Upper Surface: Creamy tan to pale grayish tan (dry). Smooth to irregularly wrinkled.
* Reproduction: Lacking apothecia and soredia.
* Photobiont: Cyanobacterial.
* Lower Surface: Coarsely mottled in color. No small, white spots (pseudocyphellae).

Lobaria anomala - Netted Lungwort, SOC
* Growth Form: Large foliose.
* Upper Surface: Light or dark brown (dry) with a network of ridges.
* Reproduction: White, gray, or blue-gray soredia on ridges of upper surface.
* Photobiont: Cyanobacterial.
* Lower Surface: Coarsely mottled in color. Light brown tomentum with scattered small, white spots (pseudocyphellae).
* Chemistry: Cortex K-. Medulla K- or K+ yellow.

Lobaria hallii - Gray Lungwort, SOC
* Growth Form: Large foliose.
* Upper Surface: Steel Gray - gray to brownish gray (dry). Rough and scabrous with often sparse tiny and fine hairs (tomentum) – use strong hand-lens to examine towards lobe tips.
* Reproduction: Soredia occur in roundish soralia on surface and margins. Apothecia uncommon.
* Photobiont: Cyanobacterial.
* Lower Surface: Pale brown or whitish tomentum.
* Chemistry: Medulla K-
* Note: Closest look-alike to L. scrobiculata, especially when wet.

Lobaria linita - Cabbage Lungwort, SOC
* Growth Form: Large foliose.
* Upper Surface: greenish to brownish or brownish gray
* Reproduction: Lacking soredia, isidia, or lobules. Apothecia common.
* Photobiont: Green algal. Internal cephalodia with cyanobacteria.
* Lower Surface: Tomentum light-colored with pale bare swellings. Black veins.
* Chemistry: Medulla K-

Lobaria pulmonaria - Lungwort
* Growth Form: Large foliose.
* Upper Surface: pale greenish to olive or brownish (dry). Strongly and coarsely reticulate-ridged.
* Photobiont: Green algal. Internal cephalodia with cyanobacteria.
* Lower Surface: Light-colored, tomentose with bare swellings.
* Reproduction: Sorediate and/or isidiate. Lobules sometimes present on older individuals. Apothecia uncommon.
* Chemistry: Medulla K+ yellow to orange, KC-

Lobaria scrobiculata appears to have a strongly oceanic affinity (Thomson 1984). East of the Cascade Range, Lobaria scrobiculata is restricted to sheltered mossy outcrop areas, often near lakes or streams (McCune and Geiser 2023). Lichens are firmly attached to their substrates, which include the bases of trees, shrub, and mossy rocks, and rarely is found on ground or soil in the Pacific Northwest (McCune and Geiser 2023).

NITROGEN FIXATION
Lobaria scrobiculata is a cyanolichen, which can fix atmospheric nitrogen into forms usable by plants and animals (McCune and Geiser 2023). In Lobaria scrobiculata, the cyanobacteria belong to genus Nostoc (Thomson 1984). Cyanobacteria are pigmented ‘blue green’, when seen through a microscope.

AIR QUALITY
Lichens are indicators of air quality. They obtain their nutrients and also acquire contaminants (pollutants) from the atmosphere. Lichen species also differ in their requirements for particular nutrients and their sensitivities to specific pollutants. The lichen’s tissue can be analyzed for a particular pollutant which summarizes or indicates its level in the air. The community of lichen species can also be used to defer information about a site’s air quality. More information can be found online for the US Forest Service: Monitoring Lichens; National Lichens & Air Quality Database; and National Atlas of Epiphytic Lichens (Jovan et al. 2021a/b); and in McCune and Geiser (2023).

Lobaria scrobiculata is rated as an oligotroph with an optimal nitrogen deposition of 0.8 kg/ha/year (McCune and Geiser 2023). As an oligotroph the lichen is most abundant where deposition averages between 0.5 to 4.2 kg of nitrogen per hectare per year; it becomes increasingly harder to find where nitrogen deposition exceeds 4.2 kg/ha/yr (USFS 2025).

CHEMICAL COMPOUNDS
Lichens produce primary and secondary chemical compounds that provide a variety of essential and specialized roles (McCune and Geiser 2023). Readers are encouraged to consult Nash (1996) and McCune and Geiser (2023) for more information.

Compounds found in Lobaria scrobiculata include: Constictic, Norstictic, Stictic, and usnic acids and scrobiculin (Goward et al. 1994).

Norstictic acid is a secondary compound that has properties to be an antioxidant, antimicrobrial, and anti-cancer (McCune and Geiser 2023).

Stictic acid is a secondary compound that has properties to be an antioxidant, antimicrobrial, anti-herbivory, and anti-cancer (McCune and Geiser 2023). In experiments studying the defense mechanisms of lichens to gastropods, stictic acid in Lobaria scrobiculata was found to be evenly distributed among reproductive and non-reproductive structures and at levels 2-3 times lower than for Lobaria pulmonaria, a close relative (Asplund et al. 2010b). Researchers concluded that these species differ in their defense strategies to gastropods. Lobaria scrobiculata concentrates the synthesis of meta-scrobiculin in its reproductive tissues and allocates to all tissues lower levels of usnic acid for its general defense. Whereas, Lobaria pulmonaria, which lacks meta-scobiculin synthesizes significantly higher concentrations of stictic acid in all tissues to generally defend itself (Asplund et al. 2010a and 2010b).

Usnic acid is a secondary compound that has properties to be an antioxidant, antimicrobrial, allelopathic, cytotoxic, anti-herbivory, anti-cancer, anti-inflammatory, neuroprotective, and analgesic/anti-pyretic; it also acts as a light screen to absorb UV either by absorbing and then re-radiating as heat or in pigments which differentially absorb or reflects at visible wavelengths (McCune and Geiser 2023). In experiments studying the defense mechanisms of lichens to gastropods, usnic acid in Lobaria scrobiculata was found to be more abundant in the upper cortex (non-reproductive tissue) and absent in soralia (reproductive tissue) (Asplund et al. 2010b). The study concluded that for Lobaria scrobiculata usnic acid functions as a solar radiation screen for cyanobacteria that underly the cortex, rather than as a defense against herbivores (Asplund et al. 2010b).

Scrobiculin is a secondary defense compound used to deter gastropods in Lobaria scrobiculata (Asplund et al. 2010b). In experiments studying the defense mechanisms of lichens to gastropods, meta-scrobiculin in Lobaria scrobiculata was found at levels five times higher in the soralia than in adjacent thallus tissue that lacked reproductive structures (Asplund et al. 2010b). Snails were found to definitively avoid the well-defended soralia. When meta-scrobiculin was removed from Lobaria scrobiculata, which can be done on living lichens through an acetone rinsing process, the snails fed more on the soralia and less on the non-reproductive tissue. This indicated that the risk of damage to reproductive tissue was greater for Lobaria scrobiculata. Further, meta-scrobiculin increases the survival rate for dispersing soralia that develop into juvenile thalli. Researchers proposed that Lobaria scrobiculata uses a strategy that targets the synthesis of defense compounds only in its reproductive structures (Asplund et al. 2010b).

SNAIL-LICHEN INTERACTIONS
Lobaria scrobiculata is known to be very palatable to gastropods (slugs and snails) living in Norway forests – where it often is observed bearing numerous grazing marks (Asplund et al. 2010a and 2010b). Snail herbivory of soralia, the lichen’s reproductive structure, is deterred significantly by meta-scrobiculin, a secondary defense chemical. In Norway, the lichen-feeding snail, Cochlodina laminata exhibits different grazing patterns based on the presence or levels of a lichen species’ secondary chemical compounds (Asplund et al. 2010b). See CHEMICAL COMPOUNDS subsection for details.

Lobaria scrobiculata propagates predominantly through vegetative (asexual) diaspores: soredia. Occasionally, sexual reproduction of the fungus occurs by spores produced from an apothecium.

SYMBIOTIC PROPAGULES
Soredia propagate the whole lichen, asexually, without re-lichenization (Budel and Scheidegger in Nash [ed.] 1996). Soredia are found on the upper surface of the thallus in specific structures called soralia. For Lobaria scrobiculata soredia are formed from the proliferation of the cyanobacterial and medullary fungal layers of the parent lichen.

GENERATIVE REPRODUCTION
Apothecia are cup- or disk-shaped fruiting bodies on the thallus in which spores, sexual reproduction of the fungus, develop (Budel and Scheidegger in Nash [ed.] 1996). For Lobaria scrobiculata, apothecia are seldom produced (McCune and Geiser 2023).

Threats to Lobaria scrobiculata have not been identified.