Cladonia foliacea (Huds.) Willd. complexe.

    Primary thallus persistent, in a carpet or low bush 3-10 cm in diameter, formed of prostrate or erect squamules 5-20 mm in height and 2-6 mm in width with an irregularly lobed to strongly divided margin and which can then form strips sometimes bordered with small black hairs. Upper surface spotted or verruculose, more or less green-yellow (the intensity of the yellow coloration depends on the usnic acid content), lower surface arachnoid, whitish to dirty yellowish. Uncommon podetions 0.5-2 cm in height ending in a closed cup (scypha) bordered by brown pycnidia. Apothecia very rare on the edge of the cups, globose, 1.5-3 mm in diameter, brown. Ascospores simple, hyaline, 8-12 x 2.5-3.5 µm. Pycnidia frequent especially at the margin of the lobes, subglobose to pyriform, dark brown to black. Conidia straight or curved 8-12 x 2.5-3.5 µm. Two chemotypes:

1) C-, K-, KC + yellow, Pd+ red. Mainly with usnic and fumaroprotocetraric acid. This is the most frequent chemotype in Europe.

2) C-, K+ yellow, KC + yellow, Pd orange → red. Mainly with usnic, fumaroprotocetraric and prosomal acid.

Species occurring mainly on the ground, typically in the cracks of limestone rocks, but also in dunes and at the foot of siliceous rocks that are not too acidic.

N.B. The "foliacea" complex is extraordinarily variable and many sp., subsp. var. and forms that today, following molecular biology work, are considered simple morphotypes (all linked by intermediaries!). We have kept them here informally and artificially at the rank of morph. to facilitate the reading of lichenological floras and inventories where they are present.

_ Cladonia angustifolia Ahti & Aptroot

Oceanic taxon characterized by its lobes very cut into strips.

_ Cladonia convoluta (Lam.) Anders

Thermophilic taxon with lobes folded into a horn coming from limestone.

_ Cladonia foliacea subsp. foliacea

A fairly common taxon considered as the type.

_ Cladonia foliacea subsp. endiviifolia (Dicks.) Boistel

Very large and very wide lobes.

_ Not to be confused with species that sometimes coexist but without yellow tones:

Cladonia firma, a maritime species of acidic soils, yellow K+ and with lobes whose lower surface is brownish (especially at the base).

Cladonia symphycarpa, yellow K+ then red.

Cladonia cervicornis, whose lower surface of the lobes is tinged with purplish and which has numerous podetions.

For more details see: R. PINO-BODAS, A.R. BURGAZ, T. AHTI, S. STEENROOS. 2018. Taxonomy of Cladonia angustiloba and related species. The Lichenologist. 50 (3): 267-282.