Cavicularia densa is the only species in the liverwort

Marchantiophyta

The Marchantiophyta are a division of bryophyte plants commonly referred to as hepatics or liverworts. Like other bryophytes, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of genetic information....

 genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Cavicularia. It is distinguished from Blasia

Blasia

Blasia pusilla is the only species in the liverwort genus Blasia. It is distinguished from Cavicularia by the presence of a collar around the base of the sporophyte capsule, and a scattered arrangement of sperm-producing antheridia....

by the absence of a collar around the base of the sporophyte

Sporophyte

All land plants, and some algae, have life cycles in which a haploid gametophyte generation alternates with a diploid sporophyte, the generation of a plant or algae that has a double set of chromosomes. A multicellular sporophyte generation or phase is present in the life cycle of all land plants...

 capsule, and a clustered arrangement of sperm-producing antheridia

Antheridium

An antheridium or antherida is a haploid structure or organ producing and containing male gametes . It is present in the gametophyte phase of lower plants like mosses and ferns, and also in the primitive vascular psilotophytes...

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Cavicularia is endemic to Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, where it grows on fine soil. The chemical compound cavicularin

Cavicularin

Cavicularin is a natural phenolic secondary metabolite isolated from the liverwort Cavicularia densa. This macrocycle is unusual because it was the first compound isolated from nature displaying optical activity due to the presence of planar chirality and axial chirality. The specific rotation for...

 was isolated from this species. The compound is notable for being the first such compound isolated from nature with optical activity.