Petalophyllum
Petalophyllum, or petalwort,[1] is a genus of liverworts in the order Fossombroniales.[2]
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The plants are small, reaching lengths of up to about 15 mm (0.6 in), and thallose; that is, the plant is not differentiated into root, stem, and leaf. The thallus consists of a midrib flanked by two wings that bear leaf-like lamellae on their dorsal surface. The ventral surface bears rhizoids and two rows of small scales.[3]
Petalophyllum is dioicous. The gametangia are individually subtended by extensions of the dorsal lamellae. Antheridia occur in rows or clusters near the apex of the thallus. Archegonia are clustered and surrounded by a pesudoperianth. Asexual reproduction occurs via apical tubers.[3]
Species
Petalophyllum lives primarily in seasonally dry habitats on disturbed soils and sand dunes in North America, western Europe, northern Africa, India, New Zealand, and Western Australia. There are currently 5 recognized species:[3][4]
- P. americanum is endemic to the Gulf Coast of the United States in Arkansas, Louisiana, Mississippi, and Texas. It was first described as the European species P. ralfsii in 1919,[5] but a detailed study later showed that the North American form is a distinct species.[4][6]
- P. hodgsoniae is known only from the type specimen, which was collected at Hawke's Bay on the North Island of New Zealand in 1947. It is considered threatened and possibly extinct.[4][7][8]
- P. indicum is found in the Punjab area of the Indian subcontinent.[4][9]
- P. preissii is known from the Swan River are of Western Australia and from the North Island of New Zealand.[4][7][8]
- P. ralfsii is found in the northern Mediterranean region as far east as Turkey, and along the Atlantic coast of Europe as far as northwest Scotland.[4][10][11]
References
- Edwards, Sean R. (2012). English Names for British Bryophytes. British Bryological Society Special Volume. 5 (4 ed.). Wootton, Northampton: British Bryological Society. ISBN 978-0-9561310-2-7. ISSN 0268-8034.
- 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.
- Crandall-Stotler, B.J. 2017. "Bryophyte Flora of North America, Provisional Publication, Petalophyllaceae". Missouri Botanical Garden. Retrieved 4 September 2017.
- Stotler, R.E. and Crandall-Stotler, B.J. "Bryophytes: Mosses, Liverworts, and Hornworts". Bryophyte Research. Southern Illinois University Carbondale. Retrieved 4 September 2017.
- Evans, A.W. 1919. Notes on North American Hepaticae - VIII. Bryologist, vol. 22, p. 54-73.
- Ford, C.H. and Crandall-Stotler, B.J. 2002. Contributions toward a monograph of Petalophyllum (Marchantiophyta). Novon, vol. 12, p. 334-337.
- Glenny, D., Fife, A.J., Brownsey, P.J., Renner, M.A., Braggins, J.E., Beever, J.E. and Hitchmough, R. 2011. Threatened and uncommon bryophytes of New Zealand (2010 Revision). New Zealand Journal of Botany, vol. 49, no. 2, p. 305-327.
- De Lange, P.J., Glenny, D., Braggins, J.E., Renner, M., von Konrat, M., Engel, J.J., Reeb, C. and Rolfe, J.R. 2015. Conservation status of New Zealand hornworts and liverworts, 2014. Publishing Team, Department of Conservation.
- Mehra, P.N. and Vashisht, B.R. 1950. Embryology of Petalophyllum indicum Kash. and a new suggestion of the evolution of thalloid habit from foliose forms. The Bryologist, vol. 53, no. 2, p. 90-114.
- 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.
- "1395 Petalwort, "Petaolphyllum ralfsii"". Joint Nature Conservation Committee, U.K. Retrieved 4 September 2017.