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

liverwort Liverworts are a group of non-vascular land plants forming the division Marchantiophyta (). They may also be referred to as hepatics. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the plant carry ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''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 Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

, where it grows on fine moist soil. Plants are

thalloid Thallus (: 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. A thallus usually names the entire ...

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 a variety ...

''. The plants are

dioicous Dioicy () is a sexual system in non-vascular plants where archegonia (female organs) and antheridia (male organs) are produced on separate plants in the gametophyte phase. It is one of the two main sexual systems in bryophytes, the other being ...

, 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. The androecium is al ...

and female

archegonia An archegonium (: archegonia), from the Ancient Greek ''ἀρχή'' ("beginning") and ''γόνος'' ("offspring"), is a multicellular structure or organ of the gametophyte phase of certain plants, producing and containing the ovum or female gamet ...

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 se ...

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 those growing in moist habitats like ''Cavicularia''. Once the young gametophyte

germinates Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an flowering plant, angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the sp ...

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 Blasiaceae is a family of liverworts with only two species: '' Blasia pusilla'' (a circumboreal species) and '' Cavicularia densa'' (found only in Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northe ...

along with the genus ''

Blasia ''Blasia pusilla'' is the only species in the liverwort genus ''Blasia''. This species establishes a symbiosis with nitrogen-fixing cyanobacteria of the genus ''Nostoc'', which are housed in special cavities, called auricles, occurring on the ven ...

'', from which it is distinguished by the absence of a collar around the base of the

sporophyte A sporophyte () is one of the two alternation of generations, alternating multicellular organism, multicellular phases in the biological life cycle, life cycles of plants and algae. It is a diploid multicellular organism which produces asexual Spo ...

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. Complex oil bodies are on ...

, ''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 185 ...

. 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 isolated from the liverwort '' Cavicularia densa''. This macrocycle is unusual because it was the first compound isolated from nature displaying optical activity solely due to the presence of ...

was isolated from this species. Cavicularin is notable for being the first compound isolated from nature displaying

optical activity Optical rotation, also known as polarization rotation or circular birefringence, is the rotation of the orientation of the plane of polarization about the optical axis of linearly polarized light as it travels through certain materials. Circul ...

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 In chemistry, axial chirality is a special case of chirality (chemistry), chirality in which a molecule contains two pairs of chemical groups in a non-planar arrangement about an axis of chirality so that the molecule is not superposable on its mi ...

References

External links

* * {{Taxonbar, from1=Q5055134, from2=Q17299167 Endemic flora of Japan Blasiales Liverwort genera Monotypic bryophyte genera Taxa named by Franz Stephani

References

Further reading

External links