North America, se Asia (including Borneo).
Genus 1, species 2 (2 in the flora).
Takakiaceae are plants of cool, cold-temperate to arctic-alpine oceanic climates. They were first collected in the Himalayas by J. D. Hooker and placed in the hepatic genus Lepidozia as L. ceratophylla by W. Mitten. The consensus has been that it was a highly unusual liverwort with affinity to the Calobryales. Distinctive features include erect shoots arising from a stolon, terete leaves, sometimes fused at or near the base and thus of 2–4 segments, naked lateral gametangia, slime cells, oil droplets, and chromosome numbers of n = 4 or 5. In 1993 sporophytes and antheridia were discovered in a population from Atka Island of the Aleutian Islands (D. K. Smith and P. G. Davison 1993). The sporophyte exhibits its affinity with the mosses, and is similar in some respects to sporophytes of the Andreaeopsida, by the columella, persistent seta, capsule that matures after seta elongation, dehiscence by a diagonal slit, and absence of elaters. R. M. Schuster (1997) suggested that gametophytically Takakia is more like a liverwort, and sporophytically more like a moss. The Japanese common name is perhaps most telling, literally translated as “puzzling moss.”