This lichen has a widespread global distribution, occurring in various regions of North America, Europe, Africa, and Asia.

Despite its broad global distribution, the conservation status of this lichen varies significantly across different biogeographic regions, with the species considered rare or threatened in some areas.

[5] The epithet "polycarpon" originates from Greek, where "poly" means "many," and "carpon" refers to "fruit" or "seed," alluding to the numerous reproductive structures characteristic of this species.

[9] Enchylium polycarpon, formerly identified under various synonyms, has undergone taxonomic revisions, resulting in a list of historical names used in scientific literature.

[2][10] Enchylium polycarpon exhibits a distinctive foliose thallus that is gelatinous and thick when hydrated, typically measuring 200–300 μm in depth.

[9][3][12] The lobe tips often exhibit a swollen, plicate (folded) appearance, contributing to a somewhat channeled effect towards the outer edges of the cushion.

[9][3] The lower thallus surface is typically paler than the upper side and is dotted with tufts of white, root-like hapters.

[9] Ascomata in the form of lecanorine apothecia are abundantly produced by Enchylium polycarpon, crowding the central region of the thallus and frequently arising directly from the marginal lobules.

The apothecial disc varies from reddish-brown to dark black, surrounded by a thick, smooth, and persistent thalline margin.

[9][3] Chemical analysis of the Enchylium polycarpon thallus has shown that it does not contain any lichen substances detectable through standard spot tests.

[9][3] The fungal component of the E. polycarpon symbiosis does not appear to produce any unique or characteristic secondary metabolites or other products.

[3] The absence of specialized lichen substances suggests that E. polycarpon likely relies primarily on the photosynthetic capabilities of its cyanobacterial photobiont, Nostoc, to meet its nutritional and functional needs.

[9] Without the production of distinctive metabolites, the lichen may derive its required resources more directly from the photosynthates provided by the Nostoc cyanobacteria.

The lichen is able to avoid the stresses of extreme solar exposure, but nevertheless prefers habitats that receive ample direct sunlight over more shaded environments.

[9] In terms of its response to human disturbance, E. polycarpon is classified as a species that occurs predominantly in natural or semi-natural habitats, with a poleotolerance value of 1 to 2 on the 4-class scale.

The lichen does not appear to extend its range into the higher-elevation oroboreal, alpine, or nival zones of mountainous regions.

[9] Collema polycarpon has been documented in localities across Europe, North America, and western Asia over past centuries.

[16][17] The 1800–1899 period saw observations reported from additional Scandinavian regions, with collections made in Öland and Härjedalen provinces of Sweden as well as in Norway.

[16][17] Records since 2000 document observations from the provinces of Ontario and Manitoba in Canada, as well as from sites in central Texas, United States.

[16][17] Frequent habitats of C. polycarpon included dolomitic and limestone rocks, as well as leaf humus in mixed forests.

[3][4] The species has also been reported from the Canadian provinces of Alberta, British Columbia, Labrador, Northwest Territories, Ontario, Quebec, and Saskatchewan.

[3] Regarding the habitat preferences of E. polycarpon, the species typically grows on hard, usually calcareous rock substrates in exposed and periodically wet microhabitats.

[9] Within the Padanian area, which encompasses the southern side of the Alps and the Po River Valley in northern Italy, the lichen is documented to be very rare.

[4] At the state level, the species is considered imperiled (S2) in Montana, possibly extirpated (SH) in Iowa and Wisconsin, and unranked (SNR) in Colorado, Georgia, Minnesota, and Wyoming.

[25] In Great Britain and Ireland, E. polycarpon has been assessed as of Least Concern by Woods & Coppins (2012) but is listed as Nationally Scarce due to the paucity of records, suggesting it may be under-reported in this region.