American Starburst Lichen

(Imshaugia placorodia)

Conservation Status
American Starburst Lichen
Photo by Luciearl
  IUCN Red List

not listed

 
  NatureServe

NNR - Unranked

 
  Minnesota

not listed

 
           
           
           
           
 
Description
 
 

American Starburst Lichen is found in the United States from Maine to Minnesota and south along the foothills of the Appalachian Mountains, in the northern Great Plains, the central and southern Rocky Mountains, and the southern Intermountain Region in the southwest. It grows on the bark of pine trees. It is almost restricted to pitch pine, jack pine, and Virginia pine in the east, and to ponderosa pine and Douglas fir in the west. It is rarely found on oak. In Minnesota it is found only on jack pine.

The vegetative body (thallus) is leaf-like (foliose) and divided into branches (lobes). It grows attached or loosely attached to the substrate (bark) by scattered, short, brown, anchoring structures (rhizines). The lobes are narrow, strap-shaped to rounded, and 1 64 to 1 16 (0.5 to 1.5 mm) in diameter. They are more or less randomly arranged and touch, crowd, or overlap adjacent lobes but are not fused to them. The margins are wavy or deeply pinnately cut, and the tips are often forked. The upper surface is grayish-green or ash-colored, smooth and somewhat shiny toward the edges, and wrinkled toward the center. There are usually tiny, globular chambers (pycnidia) embedded in the thallus with an opening through which fungal spores are released. The pycnidia look like black pinpricks in the tallus and are very conspicuous. They appear both on the margins and across the surface. The upper surface does not have powdery dull granules (soredia), shiny granules (isidia), or a chalky or “frosted” surface (pruina). The lower surface is whitish to pale brown, shiny, and somewhat wrinkled.

Disk-like, spore-producing structures (apothecia) are usually present, sometimes abundant enough to conceal the thallus. The disks are slightly raised, shaped like a plate, concave to flat or even convex, 1 16 to ¼ (2 to 7 mm) or more in diameter, pale brown or chestnut brown to dark grayish-brown. They may be flat or slightly raised, and stalkless or very short stalked. They appear near the margins on the upper surface.

 
     
 

Similar Species

 
     
     
 
Biology
 
 

Substrate

 
 

Trees

 
     
 

Growth Form

 
 

Foliose

 
     
 

Habitat

 
 

 

 
     
 

Hosts

 
 

Jack pine

 
     
 
Distribution
 
 

Distribution Map

 

Sources

4, 7, 24, 26, 29, 30, 77.

 
  5/29/2022      
         
 

Occurrence

 
 

Widespread in North America. Common in northeastern Minnesota.

 
         
 
Taxonomy
 
  Kingdom Fungi (fungi)  
  Subkingdom Dikarya  
  Phylum Ascomycota (sac fungi)  
  Subphylum Pezizomycotina  
  Class Lecanoromycetes (common lichens)  
  Subclass Lecanoromycetidae  
 

Order

Lecanorales  
 

Suborder

Lecanorineae  
 

Family

Parmeliaceae (shield lichens and allies)  
  Subfamily Parmelioideae  
 

Genus

Imshaugia  
  Mycobiont Imshaugia placorodia  
  Photobiont    
       
 

Synonyms

 
 

Parmeliopsis placorodia

 
       
 

Common Names

 
 

American Starburst Lichen

 

 

 

 

 

 

 

 

Glossary

Apothecium

An open, disk-shaped or cup-shaped, reproductive structure, with spore sacs on the upper surface, that produces spores for the fungal partner of a lichen. Plural: apothecia.

 

Foliose

Adjective: Leaf-like growth form; referring to lichens with leaf-like growths divided into lobes.
Noun: The leaf-like, vegetative body of a lichen (thallus) that has thin, flat lobes which are free from the substrate.

 

Pruina

On lichens, a thin, powdery or crystaline deposit on the surface of the thalus. It may appear chalky or frosty, and is usually white, gray, or bluish.

 

Rhizine

A root-like structure of a lichen that attaches the lower layer to the substrate.

 

Soredium

An asexual reproductive structure of a lichen in the form of a tiny dull granule on the thallus surface that can be easily brushed off. It consists of a cluster of algal cells (the photobiont) wrapped in fungal filaments (the mycobiont), but without an outer layer of protective tissue (cortex). Plural: soredia.

 

Thallus

The vegetative body of a lichen composed of both the alga and the fungus.

 
 
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Luciearl

 
    American Starburst Lichen   American Starburst Lichen  
           
 
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  Luciearl
10/24/2018

Location: Cass County

American Starburst Lichen  
           
 
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Created: 10/31/2018

Last Updated:

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