''Petalophyllum ralfsii'', the petalwort, is a

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 g ...

of the

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

Fossombroniales Fossombroniales is an order 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 c ...

.Crandall-Stotler, B.J., Stotler, R.E. and Long, D.G. 2009. Phylogeny and classification of the Marchantiophyta. Edinburgh Journal of Botany, vo. 66, no. 1, p. 155-198. It is a small green

bryophyte The Bryophyta s.l. are a proposed taxonomic division containing three groups of non-vascular land plants (embryophytes): the liverworts, hornworts and mosses. Bryophyta s.s. consists of the mosses only. They are characteristically limited in ...

that occurs in the Mediterranean region as far east as Turkey, and along the Atlantic coast of Europe as far as northwest Scotland.Rumsey, F.J., Vogel, J.C. and Russell, S.J. 2001. A study of genetic variation in the threatened hepatic ''Petalophyllum ralfsii'' (Wils.) Nees and Gottsche (Fossombroniaceae). Conservation Genetics, vol. 2, no. 3, p. 271-277. It grows primarily on moist sand dunes.

Description

The plants are small, typically less than 15 mm long by 10 mm wide (0.6 in by 0.4 in), and

thallose 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 ...

; that is, the plant is not differentiated into root, stem, and leaf. The thallus consists of a midrib flanked by two wings that bear erect, leaf-like lamellae on their

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal co ...

surface.

Distribution and habitat

''Petalophyllum ralfsii'' has a widespread distribution across Europe, primarily in the Mediterranean region. It has a specific habitat requirement, being restricted to dune slacks with certain features; it needs open, damp conditions, often growing on low hummocks rather than on the wettest parts of the slack. In Britain, the largest population occurs at

Achnahaird Ahnahaird ( gd, Achadh na h-Àirde) is a small settlement on Achnahaird Bay in Ross and Cromarty, in the Scotland, Scottish council area of Highland Council area, Highland. The beach at Achnahaird Bay was used in the filming of 'The_Eagle_(2011 ...

in Scotland, the most northerly point in its range. Other locations include

Braunton Burrows Braunton Burrows is a sand dune system on the North Devon coast. It is privately owned and forms part of the Christie Devon Estates Trust (see Tapeley Park). Braunton Burrows is a prime British sand dune site, the largest sand dune system (psam ...

and

Dawlish Warren Dawlish Warren is a seaside resort near the town of Dawlish in Teignbridge on the south coast of Devon in England. Dawlish Warren consists almost entirely of holiday accommodation and facilities for holiday-makers especially caravan sites. L ...

in Devon;

Kenfig Kenfig ( cy, Cynffig) is a village and former borough in Bridgend, Wales. It is situated inland on the north bank of the Bristol Channel, and just south-west of the M4 motorway. To the east is the town of Bridgend, at approximately , and the c ...

Aberffraw Aberffraw is a village and community on the south west coast of the Isle of Anglesey ( cy, Ynys Môn), in Wales, by the west bank of the Afon Ffraw (Ffraw River). The community includes Soar and Dothan. Located near the A4080 and the nearest ...

and the

Carmarthen Bay Carmarthen Bay ( cy, Bae Caerfyrddin) is an inlet of the South Wales coast, including notable beaches such as Pendine Sands and Cefn Sidan sands. Carmarthen Bay is partially within the Pembrokeshire Coast National Park. The Joint Nature Conserva ...

dunes in Wales;

Lindisfarne Lindisfarne, also called Holy Island, is a tidal island off the northeast coast of England, which constitutes the civil parish of Holy Island in Northumberland. Holy Island has a recorded history from the 6th century AD; it was an important ...

off the coast of Northumberland; the

Isles of Scilly The Isles of Scilly (; kw, Syllan, ', or ) is an archipelago off the southwestern tip of Cornwall, England. One of the islands, St Agnes, is the most southerly point in Britain, being over further south than the most southerly point of the ...

and the

Sefton Coast Sefton Coast is a 4605.3 hectare (11379.9 acre) Site of special scientific interest which stretches for 12 miles (20 km) between Southport and Waterloo, which is end location of Crosby Beach. The site was notified in 2000 for both its biol ...

in Merseyside. These dunes are increasingly under threat, leading to the species being classified as "vulnerable", and the British Isles may now be the liverwort's stronghold. It sometimes grows beside paths, where trampling feet keep down competing vegetation. Plants with which this liverwort may be associated include various mosses, grasses such as the common bent (''

Agrostis capillaris ''Agrostis capillaris'', the common bent, colonial bent, or browntop, is a rhizomatous and stoloniferous perennial in the grass family (Poaceae). It is native to Eurasia and has been widely introduced in many parts of the world. Colonial ben ...

''), red fescue (''

Festuca rubra ''Festuca rubra'' is a species of grass known by the common name red fescue or creeping red fescue. It is widespread across much of the Northern Hemisphere and can tolerate many habitats and climates. It is best adapted to well-drained soils in c ...

'') and Yorkshire-fog (''

Holcus lanatus ''Holcus lanatus'' is a perennial grass. The specific epithet ' is Latin for 'woolly' which describes the plant's hairy texture. Common names include Yorkshire fog, tufted grass, and meadow soft grass. In North America, where it is an invasive ...

''), the grey sedge (''

Carex flacca ''Carex flacca'', with common names blue sedge, gray carex, glaucous sedge, or carnation-grass, (syn. ''Carex glauca''), is a species of sedge native to parts of Europe and North Africa.

'') and the buck’s-horn plantain (''

Plantago coronopus ''Plantago coronopus'', the buck's-horn plantain, is a herbaceous annual to perennial flowering plant in the family Plantaginaceae. Other common names in the US and Italy include minutina and erba stella. Description ''Plantago coronopus'' prod ...

'').

References

{{Taxonbar, from=Q7171645 Fossombroniales