Identification
Trait Comparison Table
| Trait | Xanthoria parietina (Common Sunburst) | Caloplaca spp. (Orange Lichens) | Physcia aipolia (Star Rosette) |
|---|---|---|---|
| Color | Bright lemon‑yellow to deep orange; intensifies in sun | Orange to reddish‑orange; often duller | Pale gray‑green with white patches |
| Growth form | Crustose base with foliose, lobed margins | Strictly crustose, flat, tightly attached | Foliose rosettes with radiating lobes |
| Texture | Smooth to granular; soredia along lobe edges | Granular, powdery, no lobes | Smooth lobes with white pseudocyphellae |
| Fruiting bodies | Orange apothecia, disk‑like | Abundant orange apothecia, often covering thallus | White‑rimmed apothecia, contrasting with thallus |
| Substrate | Bark, rock, untreated wood, man‑made surfaces | Rocks, walls, concrete, soil | Tree bark, especially hardwoods |
| Chemical test (KOH) | Cortex K+ orange/red (parietin pigment) | Cortex K+ orange | Cortex K+ yellow, medulla K– |
| Ecological role | Nitrogen‑tolerant, thrives near bird perches and urban sites | Often colonizes nutrient‑rich stone surfaces | Indicator of clean air, less tolerant of nitrogen |