''Ricciocarpos natans'' (vernacular name: fringed heartwort) is the only species in the genus ''Ricciocarpos'', a genus of

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 ...

s in the family

Ricciaceae Ricciaceae are a Family (biology), family of Marchantiophyta, liverworts in Order (biology), order Marchantiales, with two extant genera. * ''Riccia'' * ''Ricciocarpos'' References

Ricciaceae, Liverwort families Taxa named by Ludwig ...

. It was formerly listed in 1759 as a species of ''

Riccia ''Riccia'' is a genus of liverworts in the order Marchantiales. These plants are small and thalloid, that is not differentiated into root, stem and leaf. Depending on species, the thallus may be strap-shaped and about 0.5 to 4 mm wide wi ...

'' by

Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, t ...

, but then assigned to a new genus of its own in 1829 by

August Carl Joseph Corda August Carl Joseph Corda (1809–1849) was a Czech physician and mycologist. This botanist is denoted by the author abbreviation when citing a botanical name. Early life and education Corda was born in Reichenberg (now Liberec), Bohemia on ...

. Despite having many common features with the genus ''Riccia'', its most obvious difference from that genus are the long sword-shaped purple scales that hang from the under surface of floating plants. The genus has occasionally appeared in the literature under the spelling ''Ricciocarpus'', but the spelling with an o is the original and accepted spelling. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

"''natans''" comes from the Latin word for "swimming", because plants typically float freely in ponds or quiet waters. Plants of ''R. natans'' have two very different forms, depending on the conditions under which the plant grows. One form develops in plants that grow on land (terrestrial), and another form develops when plants grow floating in the water (aquatic). The terrestrial form develops into

rosette Rosette is the French diminutive of ''rose''. It may refer to: Flower shaped designs * Rosette (award), a mark awarded by an organisation * Rosette (design), a small flower design *hence, various flower-shaped or rotational symmetric forms: ** R ...

s 25–35 millimetres across, of short and narrow branches having almost parallel sides. The more usual form is aquatic, and develops as broader, heart-shaped

thallus 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 ...

with fewer branchings and long slender purple scales hanging from the underside. The two forms are so physically different from each other that they were originally thought to be different species. ''Ricciocarpos'' is distributed globally, being found almost everywhere except the polar regions though it is rare in parts of the tropics. It may form extensive floating colonies in quiet waters, and grows readily in laboratory cultures. Although fertile plants are not unknown, mature plants bearing spore capsules are rarely found. It is therefore assumed that ''Ricciocarpos'' spreads primarily through

vegetative reproduction Vegetative reproduction (also known as vegetative propagation, vegetative multiplication or cloning) is any form of asexual reproduction occurring in plants in which a new plant grows from a fragment or cutting of the parent plant or spe ...

as the plants break apart. It has been suggested that the aquatic forms remain sterile and that sexual reproduction is largely limited to terrestrial forms, but other sources maintain that terrestrial forms are normally sterile as well.

Gallery

RicciocarposNatans8.jpg , Terrestrial form of ''Ricciocarpos''. RicciocarposNatans3.JPG , Terrestrial form of ''Ricciocarpos''. RicciocarposNatans5.jpg , Floating form with long ventral scales visible. RicciocarposNatansReddish.jpg , Aquatic form in autumn with red color.

References

External links

* * {{Taxonbar, from1=Q17280751, from2=Q2148806, from3=Q17813339 Ricciaceae Marchantiales genera Monotypic bryophyte genera Cosmopolitan species Taxa named by August Carl Joseph Corda Taxa described in 1829