What are good underwater plants that are easy to use for science projects?

I'm seeing how salinity affects growth of underwater plants....What are good plants to use for this?

What are good underwater plants that are easy to use for science projects?
Hydrilla and vallisneria along with Elodea are commonly used for science projects.



1) Hydrilla -Hydrilla is an aquatic plant, native to the cool and warm waters of Asia, Europe, Africa and Australia.



PHOTO- http://www.floridaplants.com/Eflora/hydr...



2) Vallisneria -Vallisneria is a genus of aquatic plant, commonly called eelgrass or tape grass. The genus has 6-10 species that are widely distributed, but do not grow in cold regions.



Vallisneria is a submersed plant that spreads by runners and sometimes forms tall underwater meadows. Leaves arise in clusters from their roots. The leaves have rounded tips, and definite raised veins. Single white female flowers grow to the water surface on very long stalks. Tape grass fruit is a banana-like capsule having many tiny seeds.



Photo-http://www.akvarieleks.dk/images/vallisn...



http://www.wormborough.com.au/vallisneri...



3) Elodea ----Elodea is a genus of aquatic plants often called the water weeds. Elodea is native to North America and it is also widely used as aquarium vegetation. The introduction of some species of Elodea into waterways in parts of Europe, Australia, Africa, Asia, and New Zealand has created a significant problem, and it is now considered a noxious weed in these areas.



Photo -http://www.nucleodeaprendizagem.com.br/e...
Reply:Elodea is a great one. When a length of the stem is submersed in a large test tube of water, you can count the bubbles of O2 given off the plant per unit time, thus measuring its photosythetic activity (a secondary measure of growth). Elodea grows quickly and easily in a 10-gal fish tank with aerator (increases the plant's access to CO2).