Expert: Walter Hintz - 1/28/2010

Question
What adaptations, or changes needs to be made for marine plants to move onto dry land, so these plants could distribute metabolic components (and end products) throughout and within the plant itself. [Land based plants are chemoheterotrophs]

I was thinking for marine plants to move onto land.  It must be a gradual process.  As in the plants move from saltwater to freshwater then onto land.

Adaptations I think marine plants would need are:
supportive sturctures,
transport system to carry out nutrients,
ability to reduce water loss,
regulate gas exchange,
reproductive strategies.

I'm not sure about how to describe changes needed to be made for them to move from saltwater to freshwater and finally from freshwater onto land.

I'm hoping you can elaborate or correct me if I'm wrong.
Thank you.  

Answer
It seems like you have stated correctly what must (and has) happened. Terrestrial plants have evolved from aquatic plants. To add what you have:
 The adaptation from salt water required a system to account for the difference in salinity.
 The development of structures to transmit gametes without an aquatic medium
 Flowering plants depend upon insects to carry gametes. It is interesting how insect evolution coincides with plant evolution.
 You are correct about the role supporting structures. Aquatic plants did not have to contend  with gravity.
 
If I can think of anything else I will get back to you or if you have a specific question let me know