This North American pondweed is widely recommended for demonstrating oxygen formation during photosynthesis. Elodea is cheap and easy to grow, but we find that Cabomba is a much more reliable plant for this purpose.

Practicals

• Photosynthesis -  Resources: Demonstrating oxygen formation during photosynthesis can be a tricky process. One common way is to gather bubbles of gas given off by an aquatic plant. However, Cabomba is a more reliable plant and much more effective than the traditional Elodea.
  

Teaching Topics

• Photosynthesis and respiration
  

Description

Canadian Pondweed, Elodea canadensis

A native aquatic plant of temperate areas of North America. A recorded pest on rivers and canals in the UK, particularly in the 19th century. Its distribution was aided by botanic gardens both in Britain and mainland Europe, and is now found widespread in all areas south of the Arctic, including Australia and New Zealand.

Growing and sourcing

Obtaining: Easily available from aquarium shops or pet shops that have aquarium section, and specialist science suppliers such as Blades Biological. A care sheet can be downloaded from them too 

Care: Blades Biological provide care information for both the pondweeds Elodea and Cabomba. They also supply both plants. Elodea can be kept living in an aquarium long term if anchored with gravel it should then begin to grow. Short term it can be kept in a shallow tray covered with water.

Curriculum Links   

GCSE

• AQA GCSE Science A C.1.7.2 suggested practical
• AQA GCSE Science B 3.3.1.2 suggested practical
• AQA Biology B2.3 suggested practical
• OCR GCSE Biology B4b suggested practical

A-level

• Edexcel AS/A2 3.1 Topic 5 Opportunities for practicals
• AQA Biology AS/A2 3.4.3 Opportunities for practicals
• Scottish Highers Unit 2 Metabolism Photosynthesis experiments