Primary thallus: squamulose, persistent; squamules: 8-15 mm long, 2-8 mm wide, crenate-lobate; upper surface: with waxy-appearing bumps several mm diam podetia: infrequent, 9-25 (-30) mm tall, glaucous gray, senescent parts strongly blackening, cup-forming; cups: up to 7 mm wide, bearing one or more tiers of proliferations from center surface: corticated, thickly verruculose to continuous-chinky, medullary layer emerging among chinks sometimes with a pinkish tinge Apothecia: infrequent, up to 1.5 mm diam, brown ascospores: fusiform, 9-15 x 2.5-3.5 micro meter Pycnidia: on basal squamules or on cup margins, pyriform, not restricted at the base, ostiole not apparent, with hyaline gelatin conidia: 7-8 x 1 micro meter Spot tests: K+ yellow to dingy yellow, changing to brownish, C-, KC-, P+ red, UV- Secondary metabolites: atranorin and fumarprotocetraric acid. Habitat and ecology: on soil and in rock crevices in acidic habitats; locally abundant at high elevations World distribution: Europe, Asia, North America and South America Sonoran distribution: eastern and northern Arizona. Notes: Cladonia macrophyllodes typically grows in acidic, high-mountain habitats and can be recognized by its large, gray squamules. The podetia are usually sparse or poorly developed, but when well developed the cups are wider than in any other species in the Sonoran region. It may be very similar to C. symphycarpia, which usually contains norstictic or psoromic acids besides atranorin. The latter species prefers base-rich habitats.