Petalwort (Petalophyllum ralfsii)

loading
Petalwort
loading
Loading more images and videos...

Petalwort fact file

Petalwort description

KingdomPlantae
PhylumHepatophyta
ClassHepatopsida
OrderJungermanniales
FamilyLophoziaceae
GenusPetalophyllum (1)

Petalwort is a tiny, delicate liverwort, with a flattened pale green thallus, featuring crisped raised projections called 'lamellae' (3), which radiate out from the thickened central mid-rib (4). These projections, which have something of a 'frilly' appearance, are just one cell thick, and are translucent (4). The base, which is tuberous, is embedded in the substrate (2).

All liverworts are named because the lobed species were thought to resemble the liver. During Medieval times, common belief held that the appearance of a plant indicated which part of the human body it could cure; liverworts were therefore thought to cure liver ailments (5).

Top

Petalwort biology

Liverworts, hornworts and mosses form a group of simple plants called bryophytes (2). Bryophytes lack many of the more complex structures of the higher plants, such as a vascular system, and flowers. They do not have roots, instead they have structures called 'rhizoids' which absorb water and anchor the plant to the substrate. In liverworts these rhizoids each consist of a single elongated cell (6). Like all plants, bryophytes have a life cycle consisting of two main parts, called the 'gametophyte' and 'sporophyte' generations. In bryophytes it is the gametophyte stage that is dominant (6). Plants in the gametophyte stage can reproduce sexually. Male organs (antheridia) produce sex cells, which move to the female organs (archegonia) in films of water; fertilisation occurs and a 'sporophyte' develops, which remains attached to the plant. The sporophyte releases spores, which disperse and develop into a new plant (6). Petalwort produces sporophytes from March to May, and usually disappears in winter, surviving in the form of tubers in the substrate (2).

Top

Petalwort range

This liverwort has a sparse distribution around the coastline of Britain; there are around 25 sites at present, and 4 are known to have been lost as a result of habitat destruction (3). A survey by Plantlife in 2002 found that populations in the south-west of England seem to be increasing, possibly as the result of the climatic trend towards a milder climate with wetter winters in that area (3). Populations in the rest of England seem to be remaining stable, and a known population in Wales was found to be much larger than previously thought, being larger than all other British populations put together (3).

You can view distribution information for this species at the National Biodiversity Network Gateway.
Top

Petalwort habitat

Usually inhabits damp, calcareous sand in dune slacks in wet conditions, and may even be completely inundated with water in winter (2). A particularly suitable habitat seems to be the edges of paths that are slightly disturbed (2).

Top

Petalwort status

Classified as Nationally Scarce in Great Britain and protected under Schedule 8 of the Wildlife and Countryside Act 1981. Vulnerable in Europe and listed under Appendix I of the Bern Convention, and Annex IIb of the EC Habitats and species Directive (2).

Top

Petalwort threats

This delicate liverwort faces a large number of threats, including habitat loss resulting from development and natural succession on dune slacks (3), unsuitable drainage, trampling by humans (7) and other recreational activities (2). Nutrient enrichment, resulting in unsuitable conditions for this species has occurred at some sites as a result of a large amount of dog fouling (3). Furthermore, reductions in grazing (2), as well as shading by tall vegetation and encroachment of scrub are also problems (3).

Top

Petalwort conservation

Petalwort is a UK Biodiversity Action Plan priority species, and has a species action plan to guide its conservation. It is also included in English Nature's Species Recovery Programme, which in conjunction with the Countryside Council for Wales has part-funded Plantlife to carry out research and survey work on this species (3). At present, most of the sites supporting this liverwort are protected (3).

The UK Biodiversity Action Plan for this species is available at UK BAP.
There may be further information about this species available via the National Biodiversity Network Gateway.
Top

Find out more

Top

Authentication

Information authenticated by Plantlife, the wild plant conservation charity:
http://www.plantlife.org.uk

Top

Glossary

Calcareous
Containing free calcium carbonate, chalky.
Gametophyte
A life cycle stage in plants, which has one set of chromosomes (threads of DNA protein) in the cell nucleus (a condition known as ‘haploid’), which arises from a spore (which is also haploid). Sex cells (gametes) are produced during the gametophyte stage. This is the dominant life-cycle stage in liverworts and mosses.
Natural succession
The progressive sequence of changes in vegetation types and animal life within a community that, if allowed to continue, result in the formation of a ‘climax community’ (the last stage in a succession where the vegetation reaches equilibrium with the environment).
Rhizoids
Thread-like structures that help to anchor the plant to the substrate, and absorb minerals and water. In liverworts they consist of a single cell, in mosses they are multi-cellular.
Spores
Microscopic particles involved in both dispersal and reproduction. They comprise a single or group of unspecialised cells and do not contain an embryo, as do seeds.
Sporophyte
The stage of a plant life cycle that produces spores (microscopic particles used in dispersal and reproduction). This stage is diploid (in the cell nucleus there are two sets of chromosomes - threads of DNA protein) and is dominant in ‘higher’ plants such as flowering plants.
Thallus
Type of simple plant body that does not have stems, leaves and roots.
Vascular system
In plants, the system that allows water and nutrients to move around.
Top

References

  1. National Biodiversity Network Species Dictionary (July, 2002)
    http://www.nhm.ac.uk/nbn/
  2. Church, J.M., Hodgetts, N.G., Preston, C.D. and Stewart, N.F. (2001) British Red Data Books: mosses and liverworts. Joint Nature Conservation Committee, Peterborough.
  3. Holyoak, D.T. (2002) Petalwort (Petalophyllum ralfsii): Report to Plantlife on work carried out in England and Wales during 2001 and 2002. Plantlife report number 202. ISBN 1 872613 73 X. Plantlife, London.
  4. Mosses and liverworts in Wales: Petalophyllum ralfsii. (July, 2002)
    http://home.clara.net/adhale/bryos/pralfsii.htm
  5. Egerton, H. and Jones, F. (1998) Nature Encyclopedia. Dorling Kindersley, London.
  6. Mosses and Liverworts in Wales (July, 2002)
    http://home.clara.net/adhale/bryos/
  7. UK BAP (July, 2002)
    http://www.ukbap.org.uk
X
Close

Image credit

Petalwort  
Petalwort

© Dan Wrench

Dan Wrench
Tel: +44 (0) 771 8391794
dan_wrench@yahoo.com

X
Close

Link to this photo

ARKive species - Petalwort (Petalophyllum ralfsii) Embed this ARKive thumbnail link ("portlet") by copying and pasting the code below.

Terms of Use - The displayed portlet may be used as a link from your website to ARKive's online content for private, scientific, conservation or educational purposes only. It may NOT be used within Apps.

Read more about

X
Close

MyARKive

MyARKive offers the scrapbook feature to signed-up members, allowing you to organize your favourite ARKive images and videos and share them with friends.

Play the Team WILD game:

Team WILD, an elite squadron of science superheroes, needs your help! Your mission: protect and conserve the planet’s species and habitats from destruction.

Conservation in Action

Which species are on the road to recovery? Find out now »

Help us share the wonders of the natural world. Donate today!

Blog RSS