Ludwigia stolonifera roots

We are a bit desperate and need information on Ludwigia stolonifera on behalf of our students. The plant has been cited as a good example of a species with special types of roots in aquatic plants. Apperently some roots growth upwards and others down in the sediment. We are interseted in its distribution adn if possible to obtain a picture of the plant

Birgitta Eriksson's collegues