''Cavicularia densa'' is the only species in the

liverwort The Marchantiophyta () are a division of non-vascular land plants commonly referred to as hepatics or liverworts. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

''Cavicularia''. The species was first described in 1897 by

Franz Stephani Franz Stephani (15 April 1842 – 23 February 1927) was a German bryologist specializing in liverworts. This botanist is denoted by the author abbreviation when citing a botanical name. Stephani was born in Berlin, Province of Brandenburg, i ...

, and is endemic to Japan, where it grows on fine moist soil. Plants are

thalloid Thallus (plural: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. Many of these organisms were ...

and flattened, with distinct upper and lower surfaces and a faint central strand. Thin scales grow from the underside in two rows, and in the region between the scales and the central strand are small ear-shaped ''domatia'' which harbor colonies of the blue-green alga ''

Nostoc ''Nostoc'', also known as star jelly, troll’s butter, spit of moon, fallen star, witch's butter (not to be confused with the fungi commonly known as witches' butter), and witch’s jelly, is the most common genus of cyanobacteria found in var ...

''. The plants are

dioicous Dioicy () is a sexual system where archegonia and antheridia are produced on separate gametophytes. It is one of the two main sexual systems in bryophytes. Both dioicous () and monoicous gametophytes produce gametes in gametangia by mitosis ra ...

, with the male

antheridia An antheridium is a haploid structure or organ producing and containing male gametes (called ''antherozoids'' or sperm). The plural form is antheridia, and a structure containing one or more antheridia is called an androecium. Androecium is also ...

and female archegonia produced by separate plants. Plants may also reproduce asexually from multicellular gemmae produced in crescent-shaped receptacles on the thallus surface. The spores are spherical and apolar, with a surface devoid of ornamentation except for tiny papillae.

Gametophyte A gametophyte () is one of the two alternating multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. The gametophyte is the ...

development is endosporic, so that cell divisions begin inside the spore wall. This pattern of development is normally found in liverworts from xeric environments, rather than the those growing in moist habitats like ''Cavicularia''. Once the young gametophyte germinates and ruptures the spore coat, it produces a multi-layered mass from which the adult plant will develop. ''Cavicularia'' is classified in the family Blasiaceae along with the genus '' Blasia'', from which it is distinguished by the absence of a collar around the base of the sporophyte capsule, and a clustered arrangement of sperm-producing

. Like ''Blasia'', plants of ''Cavicularia'' possess domatia containing colonies of the blue-green alga ''

''. Despite their similarities and traditional classification together, the two genera do not group together as a clade in some recent analyses. While ''Blasia'' attaches to the base of the complex-thalloid clade

Marchantiopsida Marchantiopsida is a class of liverworts within the phylum Marchantiophyta. The species in this class are known as complex thalloid liverworts. The species in this class are widely distributed and can be found worldwide. Phylogeny Based on the w ...

, ''Cavicularia'' lies at the base of the simple-thalloid and leafy clade

Jungermanniopsida Jungermanniopsida is the largest of three classes within the division Marchantiophyta (liverworts). Phylogeny Based on the work by Novíkov & Barabaš-Krasni 2015. Taxonomy * Jungermanniidae Engler 1893 ** Jungermanniales von Klinggräff 1858 ...

. Thus, the genus has been dubbed "problematic", but modifications to its taxonomic placement await further investigation. The chemical compound

cavicularin Cavicularin is a natural phenolic secondary metabolite Secondary metabolites, also called specialised metabolites, toxins, secondary products, or natural products, are organic compounds produced by any lifeform, e.g. bacteria, fungi, animal ...

was isolated from this species. Cavicularin is notable for being the first compound isolated from nature displaying optical activity solely due to the presence of

planar chirality Planar chirality, also known as 2D chirality, is the special case of chirality for two dimensions. Most fundamentally, planar chirality is a mathematical term, finding use in chemistry, physics and related physical sciences, for example, in astrono ...

and axial chirality.

References

External links

* * {{Taxonbar, from1=Q5055134, from2=Q17299167 Endemic flora of Japan Blasiales Liverwort genera Monotypic bryophyte genera

References

Further reading

External links