Gritty British soldiers lichen

The primary thallus of Cladonia floerkeana is persistent, made up of small, lobed squamules (scales) that measure 1–3 mm in length and 1–2 mm in width. These squamules are esorediate, meaning they lack powdery reproductive structures known as soredia. The basal squamules are small, persistent, and often inconspicuous, with an orange tinge toward the base of the lower surface. The secondary structures, or podetia, are frequent and grow up to 2 cm tall but are often shorter. They are pale to dark grey, with a brownish tinge in exposed sites. The podetia may remain unbranched or branch sparingly near the apices. Their surface is highly variable: they may be entirely corticate, partially decorticate (especially toward the apices), granular-sorediate in patches, or densely squamulose throughout. They have been described as resembling "scraggly white fingers with lumpy surfaces". The surface of the podetia is usually corticate (covered in a thin fungal layer), with occasional granules or small scales. Microscopically, the podetial wall has several distinct layers: an upper cortex of densely packed hyphae, an algal layer containing round or shriveled algal cells loosely associated with hyphae, and a medullary layer made up of loosely interwoven hyphal threads forming a fibrous network. …

Cladonia floerkeana has a broad but patchy distribution, with records from multiple continents. In Honduras, it is rare and has been observed growing on wooden fences, suggesting it may be frequently overlooked in this region. The species is also found in Chile, where it is considered very rare, and in eastern North America, ranging from Florida (very rare) to Newfoundland. In Europe and Australasia, its presence has been confirmed, though the full extent of its distribution is poorly understood, partly due to confusion with the similar species Cladonia macilenta. Additional records indicate its presence in Melanesia, including Papua New Guinea, as well as in regions of North and South America, Europe, Africa, Asia (e.g., Japan and Taiwan), and Oceania, including New Caledonia, Australia, and New Zealand. The species grows in nutrient-poor acidic soils and is commonly found in habitats such as heathlands, boreal forests, and areas recovering from disturbance, including post-fire landscapes. It grows on a variety of substrates, including soil, humus, rocks, and sand, and is occasionally found on decaying wood. It has been observed in geothermal vent areas in Japan, where it tolerates extreme conditions, including high surface temperatures (above 40°C), root-zone temperatures exceeding 70°C, and soil pH levels between 5 and 5.5. Despite this adaptability, C. …

As a pioneer species, C. floerkeana often establishes early in succession, forming part of a characteristic "cup lichen" community. These adaptations enable it to occupy niches too harsh for vascular plants or mosses, reducing competition in these environments. The podetia show a high degree of variability, ranging from entirely decorticate surfaces to densely squamulose ones, allowing the lichen to adapt to a wide range of environmental conditions and substrate types. The species demonstrates a preference for environments with low atmospheric nitrogen deposition, where it is more abundant compared to high-deposition areas. High nitrogen deposition can reduce lichen diversity and promote algal growth, which may outcompete C. floerkeana. This sensitivity to nitrogen deposition further limits its distribution in areas subject to elevated nitrogen levels. In high-nitrogen environments, C. floerkeana is often replaced by nitrogen-tolerant species, such as Cladonia macilenta and Cladonia ramulosa. Ecologically, C. floerkeana demonstrates a high reproductive effort, producing abundant apothecia on its podetia, which die after spore release. This strategy facilitates its rapid colonisation of new substrates. …