Thank you for your great question. The short answer is that, according to the Western Australian Department of Agriculture and Food, you can legally grow Hydrilla in WA, and use it in biological experiments and investigations. See https://www.agric.wa.gov.au/organisms/126995
However, this does not apply to all states and territories. According to the Australian Government Department of Environment, it is noted as a declared weed in Western Australia and Tasmania. Its use is permitted in WA but in Tasmania, where it does not occur naturally, it may not be sold or used. See:
- http://www.environment.gov.au/cgi-bin/biodiversity/invasive/weeds/weeddetails.pl?taxon_id=9576# (see management tab)
For general information regarding the importation of other plants or organisms into WA, see https://www.agric.wa.gov.au/bam/legislation-importing-western-australia. The status of a particular organism can be checked on the Western Australian Organism List (WAOL) see https://www.agric.wa.gov.au/organisms. Unlisted organisms require a permit for importation.
As often happens, your query opens up a number of associated questions. This is also an opportunity to address some of these.
Hydrilla (H verticillata) is an aquatic plant native to parts of Asia and Northern Australia (NT and Qld) where it grows in waterways, lagoons and estuaries. It now occurs naturally in all states and territories except the ACT and Tasmania. It is very similar to a number of other aquatic plants including Elodea.
Hydrilla is extremely robust and able to thrive in a wide range of temperature, light and salinity conditions. With the potential to create severe environmental plant blooms and waterway obstruction, this is not usually a problem in Australia. However, it is a major problem in North America.
Elodea (E Canadensis), is a similar aquatic plant that is native to North America, introduced through its use in aquaria. It can also create severe blooms and clog waterways, and is regarded as a greater environmental problem in Australia. For this reason, it is banned from sale in most of Australia, with the exception of Victoria. See https://www.southernbiological.com/biology/specimens/living-specimens/plants-and-physarum/l2-15-elodea-anacharis-live-victoria-only/ (Updated May 2019)
Availability of Hydrilla
Hydrilla is not widely commercially available as live plants, however, we have located one possible source. See http://www.watergardenparadise.com.au/submergedplants.php.
Alternatively, as Hydrilla occurs naturally in many waterways, you may be able to collect it yourself. Responsible management of it would include destroying any remaining plant material at the end of the activity to ensure that it is not allowed to enter any waterways where it does not already exist.
The context of this question, and a request for help
We understand that the intended use is to allow the plants to photosynthesise under water and to observe and capture the oxygen bubbles that are generated in an inverted test tube. In the past, Elodea has been used in such activities. However, because of its declared pest status, this is no longer permitted, except in Victoria. The possible use of Hydrilla is being considered for this activity.
Although we have not field tested it, we think that under favourable conditions Hydrilla produces oxygen at a rate suitable for the above activity. Given the precautions listed above, there would seem to be no reason not to use this plant in those parts of Australia where it already occurs naturally. However, there remain significant parts of Australia where this is not appropriate, especially Tasmania and the ACT.
Science ASSIST would welcome any suggestions of other more environmentally friendly aquatic plants that may suit this activity.