World distribution: The world distribution includes Europe, North America, Asia, Australia, and New Zealand (Carlin & Owe-Larsson 1994). It has a southwestern distribution in Norway (Nordnes 1982a) and Sweden (11 localities; Carlin & Owe-Larsson 1994), and is also reported from Finland and continental Europe
Ecology: Results. The species was not given priority during the field work, and no localities were visited. Ecological label data were sparse. In one locality the species was found on open, gently SE-sloping rocks near a river. Another label mentioned a railway station as the habitat. Discussion. The occurrence at a railway station indicates that C. polycarpoides is tolerant of disturbance, as it is in the U.S.A. where it is a common species on road sides (Carlin & Owe-Larsson 1994). In Sweden it grows in common habitats, like exposed sandy soil and thin soil over rock outcrops (Carlin & Owe-Larsson 1994)
Threats: Results. None. Discussion. A recent Swedish study concluded that the species had small but stable populations that were not acutely threatened (Carlin & Owe-Larsson 1994). It is probably an early colonizer like most other Cladonia species
Status: Without well-developed podetia, the species cannot on be separated morphologically from the common C. cervicornis, C. subcervicornis, and even C. macrophylla. Field studies therefore require extensive collection for TLC examination. Since the species is difficult to recognize in the field and its habitat is not rare or threatened in Norway, we assume the species is overlooked. There are no protected localities
Specimens in other herbaria, litterature, etc.