Cladonia squamosa s. lat.

Podetia 2–5 cm tall, green to grey-brown, the branching irregular, the apices pointed or with an irregular, usually narrow (to 2 mm diam.) perforate trumpet like cup (up to twice as wide with a glossy chestnut interior in well-developed heathland morphs), the cups often dentate and proliferating from the rim, the surface scabrid, covered in numerous squamules, particularly at the base, these derived from peeling of the cortex, often leaving extensive decorticate areas (in contrast, large heathland morphs have a cracked cortex with few peeling squamules). Basal squamules to 2 mm diam., indented, often forming compact mats. Apothecia and pycnidia brown, at the apices of podetia; apothecia rather small, rare, when well-developed often in corymbose clusters. Thallus C–, K–, KC–, Pd–, UV+ vivid white (squamatic and ± barbatic acids; chemotype A) or C–, K+ yellow-orange, KC–, Pd+ orange, UV– (thamnolic and ± barbatic acids; chemotype B).

Very variable with typical morphs characterised by the perforate podetia, numerous peeling squamules and absence of soredia. In some morphs, typically in open low productivity heaths, the podetia have a ± intact cortex and a more strongly developed cups, in which case they can resemble Cladonia crispata var. cetrariiformis. In these cases the surface of the podetia is nearly always finely roughened and scabrous, a feature absent in the other species.

Populations (common throughout our region) with a more robust and consistently more densely squamulose thallus, which reacts C–, K+ yellow-orange, KC–, Pd+ orange, UV– (thamnolic and ± barbatic acids), have been separated as Cladonia squamosa var. subsquamosa. This taxon is considered to be a chemotype of C. squamosa and not worthy of formal recognition since thamnolic and squamatic acids are very closely related biosynthetically and the morphological distinction is questionable. The distinctive robust heathland morph with wide cups with a glossy chestnut interior is mainly the subsquamosa chemotype but may vary, sometimes apparently within the same thallus. For the time being this taxa and Cladonia squamosa var. squamosa are still being recorded by the BLS mapping scheme.