Shield Pennywort, Hydrocotyle, Whorled Pennywort, Brazilian Pennywort, Whorled Marshpennywort, Whorled Marsh Pennywort, Whorled Pennyroyal

WEEDS AUSTRALIA - profiles

View all images

Quick Facts

Quick facts

  • Shield Pennywort is native to the eastern states of Australia, Papua New Guinea, most of the Americas and some parts of Africa.
  • It is not native to Western Australia and posses a risk of becoming a weed there, similar to Hydrocotyl (Hydrocotyle ranunculoides).
  • Shield Pennywort is a creeping, perennial, semi-aquatic herb with creamy-white flowers.
  • Shield Pennywort can be controlled with herbicides.

What Does It Look Like?

What is it?

Shield Pennywort (Hydrocotyle verticillata) is a semi-aquatic, perennial herb with creeping stems which roots at the joints of its stems. The leaves are circular, 20-40 mm in diameter, with a leaf stalk up to 25 cm long, attached centrally on the under surface of the leaf. The leaf margins are crenate (with shallow rounded teeth). The inflorescence (floral structure) is simple or has two or more branches arranged in 2–7 whorls (rings).

The flowers are sessile (stalkless) and in groups of 2–5. The stalk of the peduncle (flowering head stalk) is about half as long as the leaf stalk. The petals are creamy-white and sit on top of an ovary with two lobes.

The fruit is ribbed, laterally flattened and about 2 mm long (Harden 2007b).

Flower colour

White

Growth form (weed type/habit)

Herb, Aquatic

Where it currently grows? Preferred habitat

Shield Pennywort is an aquatic herb growing in fresh water swamps, lagoons and along streams and rivers (Harden 2007b).

Are there similar species?

Shield Pennywort is easily confused with the introduced species Hydrocotyle bonariensis, but the two species may be distinguished as H. bonariensis has more complex flower heads and heart-shaped fruit with prominent veins whereas H. verticillata has round fruit with inconspicuous veins (Harden 2007a, 2007b).

Why Is It A Weed?

What are its impacts?

Shield Pennywort (Hydrocotyle verticillata) is native to Australia. It is not considered to be a weed in any Australian State except Western Australia. The Western Australian Department of Agriculture and Food has listed it as a category P1/2 weed as it is considered to be potentially invasive there, but notes that it is not known to occur in that state (Department of Agriculture and Food 2008).

Native ecosystems: Shield Pennywort has very similar characteristics to Hydrocotyl (Hydrocotyle ranunculoides) which is a serious weed in Western Australia (Randall 2008 pers. comm.). By forming extensive mats over the water, Hydrocotyl disrupts the ecology and the recreational uses of waterways. Dense floating mats of Hydrocotyl interfere with navigation, irrigation and river ecology. They can also constitute a safety hazard if humans or animals fall through a mat or are dragged under by the river current (Agriculture Protection Board of Western Australia 1993; Canning River Regional Park Management Plan 1997-2007).

How does it spread?

Shield Pennywort is dispersed by seed and stem segments which root at nodes (Harden 2007b).

What is its history in Australia?

Shield Pennywort is native to the eastern coast of Australia, and south through to Adelaide (Harden 2007b).

How To Manage It?

Best practice management

Chemical control: Some herbicides can be used whenever green leaf surface is exposed, while others should be used only while the plant is actively growing (Department of Agriculture and Food 2008). Care should be taken when applying herbicides to aquatic plants to avoid contaminating water.

Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au 

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

Shield Pennywort is a perennial that flowers from November to April (Harden 2007b).

Where Is It Found?

Which states and territories is it found?

Native to NSW, QLD, SA, VIC
Not native to WA

What areas within states and territories is it found?

The Australian native species, Shield Pennywort (Hydrocotyle verticillata), occurs along the east coast of Australia from Queensland to Victoria and in the vicinity of Adelaide in South Australia (AVH 2008). There are 2 records of the plant in the south-west of Western Australia around 1900 (State Herbarium of South Australia 2008), although it is currently reported as not being present in the state (Department of Agriculture and Food, Western Australia 2008). In some areas of Queensland it is considered to be rare (McNeill 2005).

Where does it originate?

Hydrocotyle verticillata is native to Australia and commonly known as Shield Pennywort. Shield Pennywort is widespread throughout much of the tropics and subtropics including Australia, New Guinea, South Africa, Angola, Uganda, the United States of America, Central and South America (Aluka 2008). It is used extensively in aquaria and generally known as Whorled Pennywort or Brazilian Pennywort. It is not considered to be a weed in any Australian state except Western Australia (Department of Agriculture and Food, Western Australia 2008), where it is listed due to its similarity to the serious weed Hydrocotyl (Hydrocotyle ranunculoides) (Randall 2008 pers. comm.).

For further information and assistance with identification of Shield Pennywort, contact the herbarium in your state or territory.

 

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

WA

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

NO

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

NO

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Hydrocotyle verticillata

Other scientific names (synonyms)?

Hydrocotyle vulgaris L. (misapplied by G.Bentham, Fl. Austral. 3: 339 (1867); F.M.Bailey, Syn. Queensl. Fl. 208 (1883); F.J.H. von Mueller, Syst. Census Austral. Pl. 62 (1882); C.Moore, Census Pl. N.S.W. 29 (1884); F.J.H. von Mueller, Second Syst. Census Austral. Pl. 106 (1889), p.p.; J.H.Maiden & E.Betche, Census N.S.W. Pl. 160 (1916); A.J.Ewart, Fl. Victoria 894 (1931); J.M.Black, Fl. S. Austral. 1st edn, 3: 436 (1926); J.M.Black, Fl. S. Austral. 2nd edn, 3: 651 (1952))

Does it have other known common name(s)?

Hydrocotyle, Whorled Pennywort, Brazilian Pennywort, Whorled Marshpennywort, Whorled Marsh Pennywort, Whorled Pennyroyal

Bibliography

Australian Plant Census (2011) available at http://www.anbg.gov.au/cgi-bin/apclist.

Australia's Virtual Herbarium (AVH) (2008). Council of Heads of Australian Herbaria (CHAH). Available at http://www.chah.gov.au/avh/index.jsp 

Balciunas, J.K., Grodowitz, M.J., Cofrancesco, A.F. & Shearer, J.F. (2002) Hydrilla, in R. Van Driesche et al., Biological Control of Invasive Plants in the Eastern United States, USDA Forest Service. Available at http://www.invasive.org/eastern/biocontrol/7Hydrilla.html 

Bowmer, K.H., Mitchell D.S. & Short D.L. (1984) Biology of Elodea canadensis Mich. and its management in Australian irrigation systems. Aquatic Botany 18: 231-238. Abstract available at http://md1.csa.com/partners/viewrecord.php?requester=gs&collection=ENV&recid=785371&q=Biology+of+Elodea+canadensis+Mich.+and+is+management+in+Australian+irrigation+systems&uid=790304295&setcookie=yes 

Cook, C.D.K. & Lüönd, R. (1982) A revision of the genus Hydrilla (Hydrocharitaceae). Aquatic Botany 13: 485-504.

Cowie, I.D., Short, P.S. & Osterkamp Madsen, M. (2000) Floodplain Flora. A flora of the coastal floodplains of the Northern Territory, Australia. Flora of Australia Supplementary Series No. 10. Australian Biological Resources Study (ABRS), Canberra.

Cronk, J.K. & Fennessy, M.S. (2001) Wetland Plants: Biology and Ecology. Lewis Publishers.

CSIRO Entomology (2007) Biological control of the aquatic weed Hydrilla in the USA. CSIRO Invasive Plants Profile - Project. Available at http://www.csiro.au/science/ps335.html 

Global Invasive Species Database (2006) Hydrilla verticillata (aquatic plant). National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG). Available at http://www.issg.org/database/species/ecology.asp?si=272&fr=1&sts=sss 

Gopal, B. & Goel, U. (1993) Competition and allelopathy in aquatic plant communities. The Botanical Review 59: 155-210.

Grodowitz, M.J., Center, T.D., Cofrancesco, A.F. & Freedman, J.E. (1997) Release and establishment of Hydrellia balciunasi (Diptera, Ephydridae) for the biological control of the submersed aquatic plant Hydrilla verticillata (Hydrocharitaceae) in the United States. Biological Control 9: 15-23. Abstract available at http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WBP-45MFTKY-1W&_user=830463&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000044808&_version=1&_urlVersion=0&_userid=830463&md5=da7d01e5dea18070d37f179be4e9a2e0 

Grodowitz, M.J. et al. (2004) Hydrellia pakistanae and H. balciunasi, insect biological control agents of Hydrilla: boon or bust? In J.M. Cullen et al. (eds), Proceedings of the XI International Symposium on Biological Control of Weeds, Canberra, Australia, 27 April-2 May 2003, pp. 529-538. CSIRO Entomology, Canberra. Available at http://www.ento.csiro.au/weeds/BC_weeds.pdf 

Gupta, O.P. (1987) Aquatic Weed Management. Today & Tomorrow's Printers & Publishers, New Delhi.

Holm, L., Doll, J., Holm, E., Pancho, J. & Herberger, J. (1997) World Weeds. John Wiley & Sons, New York.

Jacobs, S.W.L. (1993) Hydrocharitaceae, in G.J. Harden (ed.), Flora of New South Wales Volume 4, pp. 11-16. New South Wales University Press, Kensington. Available on New South Wales FloraOnline at http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Hydrilla~verticillata 

Kleinschmidt, H.E. & Johnson, R.W. (1977) Weeds of Queensland. Queensland Department of Primary Industries.

Navie S. (2004). Declared Plants of Australia. An identification and information system. Centre for Biological Information Technology: Brisbane. [CD-ROM]

Netherland M.D. (1997) Turion ecology of Hydrilla. Journal of Aquatic Plant Management 35: 1-10. Available at http://sgnis.org/publicat/papers/neth1997.pdf 

Parsons, W.T. & Cuthbertson, E.G. (2001) Noxious Weeds of Australia, 2nd edn. CSIRO, Collingwood.

PIER (2008) Hydrilla verticillata. Pacific Island Ecosystems at Risk (PIER), Institute of Pacific Islands Forestry. Available at http://www.hear.org/pier/species/hydrilla_verticillata.htm 

Ramey, V. (2001a) Non-native Invasive Aquatic Plants in the United States: Hydrilla verticillata (L.f.) Royle. Center for Aquatic and Invasive Plants, University of Florida and Sea Grant. Available at http://plants.ifas.ufl.edu/seagrant/hydver2.html  

Ramey, V. (2001b) Non-native Invasive Aquatic Plants in the United States: Lagarosiphon major (Ridley) Moss. Center for Aquatic and Invasive Plants, University of Florida and Sea Grant. Available at http://plants.ifas.ufl.edu/seagrant/lagmaj2.html 

Richardson, F.J., Richardson, R.G. and Shepherd, R.C.H. (2006).Weeds of the south-east: An identification guide for Australia. R.G. & F.J. Richardson. Meredith, Victoria.

Romanowski, N. (1998) Aquatic and Wetland Plants. UNSW Press, Sydney.

Rye, B.L. (1992) Hydrocharitaceae, in J.R. Wheeler (ed.) et al., Flora of the Kimberley Region. WA Department of Conservation and Land Management, Como.

Sainty, G.R. & Jacobs, S.W.L. (1981) Waterplants of New South Wales. Water Resources Commission of New South Wales.

Sainty, G.R. & Jacobs, S.W.L. (2003) Waterplants in Australia, 4th edn. Sainty & Associates Pty Ltd, Potts Point.

Shearer, J.F. & Nelson, L.S. (2002) Integrated use of endothall and a fungal pathogen for management of the submersed aquatic macrophyte Hydrilla verticillata. Weed Technology 16: 224-230. Abstract available at http://wssa.allenpress.com/perlserv/?request=get-document&issn=0890-037X&volume=016&issue=01&page=0224 

Soerjani, M. (1986) Environmental considerations in the novel approach of aquatic vegetation management. In K. Noda & B.L. Mercado (eds), Weeds and the Environment in the Tropics, pp. 33-49. Proceedings of the 10th Asian-Pacific Weed Science Society Conference, Chiang Mai, Thailand, November 1985. Asian-Pacific Weed Science Society, Japan International Cooperative Agency.

Spencer, D.F. & Ksander, G.G. (1991) Comparative growth and propagule production by Hydrilla verticillata grown from axillary turions or subterranean turions. Hydrobiologia 222: 153-158. Abstract available at http://www.springerlink.com/content/u31un285q3436570/ 

Stanley, T.D. & Ross, E.M. (1989) Flora of south-eastern Queensland, Volume 3. Queensland Department of Primary Industries, Brisbane.

Stephens, K.M. & Dowling, R.M. (2002) Wetland Plants of Queensland. A Field Guide. CSIRO, Collingwood.

Swarbrick, J.T., Finlayson, C.M. & Cauldwell, A.J. (1995) Hydrilla verticillata (L.f.) Royle, in R.H. Groves, R.C.H. Shepherd & R.G. Richardson (eds), The Biology of Australian Weeds Volume 1. R.G. & F.J. Richardson, Melbourne. This reference summarises many features of Hydrilla and includes an extensive reference list.

Tasmanian Department of Primary Industries and Water (2008) Weeds, Pests and Diseases - Hydrilla Hydrilla verticillata (L.f.) Royle - Statutory Weed Management Plan. Available at http://www.dpiw.tas.gov.au/inter.nsf/WebPages/TPRY-5D7VZK?open . Images available at http://www.dpiw.tas.gov.au/inter.nsf/WebPages/SLEN-5NKA8S?open 

Weber, E. (2003) Invasive Plant Species of the World. CABI Publishing, Wollingford.

Western Australian Herbarium (undated) Hydrilla verticillata (L.f.) Royle, in FloraBase - The Western Australian Flora. Department of Environment and Conservation. Available at http://florabase.calm.wa.gov.au/browse/profile/166 

Yeo, R.R., Falk, R.H. & Thurston, J.R. (1984) The morphology of Hydrilla (Hydrilla verticillata (L.f.) Royle). Journal of Aquatic Plant Management 22: 1-17.

Blackberry – a community-driven approach in Victoria

Blackberry the weed (Rubus fruticosus aggregate) was first introduced to Australia by European settlers in the mid-1800s as a fruit. It was recognised as a weed by mid-1880s. Blackberry is a serious issue across Australia. It is estimated that blackberry infests approximately 8.8 million hectares of land at an estimated cost of $103 million in annual control and production losses.

Read Case Study