World distribution: The species occurs in Europe, North Africa, the Middle East, North America, and New Zealand (Degelius 1954, 1974). It is widely distributed in Europe, and especially frequent in the western part. According to Degelius (1954), it is one of the most common Collema species in many areas, e.g. in the British Isles. Collema crispum is mainly a southern species in the Nordic countries, occurring in Denmark, the Faroe Islands, and Sweden (from Skåne to Uppland) (Degelius 1954, 1974, Santesson 1993)
Ecology: Discussion. The species was collected on sloping, moist calcareous rock (Degelius 1982). The species grows on a wide range of substrates including soil, rock, bark, and wood; the most common substrates are more or less calciferous soil, limestone, chalk, more or less calciferous sandstone, and mortar (Degelius 1954). In Scandinavia, it is mainly terricolous. The most important habitats are man-made, and include bare patches in lawns, roadsides, ditches, claypits, limestone quarries, and dusty walls. Natural habitats are mainly rocks and boulders of limestone and sandstone. The species prefers somewhat moist and shady habitats, and sometimes occurs on periodically submersed rocks. The species often grows together with C. tenax, sometimes also with C. limosum, and is regarded as a pioneer lichen and a weak competitor (Degelius 1954)
Threats: Results. None. Discussion. A pioneer lichen should be threatened by natural vegetation dynamics
Status: The single Norwegian collection was made in 1975, and no later information about the population is available. The species was abundant and the specimens well developed in 1975, although without apothecia (Degelius 1982). The locality is not protected. The Norwegian population is the northernmost in Europe, and widely disjunct from the nearest Swedish localities. The species is insufficiently known in Norway, and possibly overlooked
Notes: The Norwegian material belongs to var. crispum.
Specimens in other herbaria, litterature, etc.