1.   A terrestrial plant will always be stunted in growth and assimilation and can never be a match for a true aquatic plant.

2.   Devonian plants, the earliest known terrestrial plants, are seen at Rhynie, and are regularly used by palaeobotanists to develop techniques and expertise.

3.   Terrestrial plants were too tough for them to digest, so the creatures had to return to the water to dine on soft sea species.

4.   Water varieties of terrestrial plants, such as irises and cannas, are other possibilities.