Punctelia rudecta
Punctelia rudecta
Family: Parmeliaceae
Rough Speckled Shield (Punctelia rudecta) is a common foliose lichen found on tree bark throughout much of eastern and central North America. It forms loosely attached rosettes with broad, rounded lobes and a gray to blue-gray thallus, often contributing significantly to mature bark-lichen communities.
This page documents field observations used for identification. Visual presentation and artistic interpretation are handled separately in the Gallery section, Rough Speckled Shield.
Identification
- Growth form: Foliose
- Thallus color: Pale gray to blue-gray
- Lobes: Broad, rounded, typically overlapping
- Surface texture: Slightly roughened or matte, sometimes appearing faintly speckled
- Lower surface: Black to dark brown with pale margins
- Rhizines: Simple to sparsely branched
- Reproductive structures: Apothecia uncommon; soredia typically absent or sparse
The overall impression is of a coarse, sturdy foliose lichen, larger and thicker than most Physcia species.
Similar Species
Eastern Speckled Shield (Punctelia bolliana)
Often confused with P. rudecta, but typically shows more distinct pale spotting and a slightly smoother thallus. Separation can be subtle and may require close inspection or chemical tests.
Physcia and Phaeophyscia species
Usually smaller, with narrower lobes and a more delicate appearance. These species often grow intermixed with Punctelia but do not form large, dominant rosettes.
Other Parmeliaceae
Several gray foliose lichens may appear similar at a glance, but Punctelia rudecta stands out by its size, lobe breadth, and subdued surface texture.
Habitat and Distribution
Rough Speckled Shield is most often found on:
- Tree trunks and large branches
- Hardwoods, occasionally conifers
- Well-lit to moderately shaded sites
It tolerates a wide range of conditions and is frequently encountered in urban, suburban, and natural woodland settings.
Notes
Because Punctelia rudecta commonly grows in mixed-species colonies, careful attention to lobe size, texture, and overall growth form helps avoid confusion. When uncertain, comparison with confirmed Punctelia specimens or consultation with regional keys is recommended.
Gallery
Representative photographs of this species can be found in the Gallery section: