Primary thallus: squamulose, persistent or evanescent; squamules: 1.5-9 mm x 0.5-2 mm, ± laciniate, esorediate podetia: up to 2. 5 cm tall, 0.3-2 mm wide, whitish gray, without cups, unbranched to sparsely dichotomously branched, occasionally richly branched at apices, tips blunt to acute, branches flexuose or recurved surface: decorticate or cortex sparsely verruculose-granulose, or sorediate, occasionally microsquamulose, somewhat striate, very hard inner medulla usually exposed Apothecia: rather frequent, 0.3-1.5 mm wide, red brown spores: oblong, 7-13 x 2.5-3.5 micro meter pycnidia: on primary squamules or at tips of podetia, with hyaline gelatin conidia: 4-8 x 0.5 micro meter Spot tests: K-, KC-, C- and P+ red Secondary metabolites: fumarprotocetraric acid (chemistry more variable in other areas; Ahti 2000). Habitat and ecology: on bare mineral soil, especially trail banks, collected at 1340-1800 m in Chihuahua World distribution: North America (Mexico), West Indies and South America, mainly tropical Sonoran distribution: Chihuahua. Notes: Cladonia cartilaginea is a widespread farther south in Mexico, where it is a short-lived pioneer species of disturbed habitats. It is easily overlooked, or confused with a more common species with simple podetia, C. subradiata, in Mexico. It can be recognized by its very hard inner medulla (difficult to cut with a razor blade!), its poor development of soredioid bodies, and the absence of cups.