Seatrees, as their name indicated, were underwater woody plants with a main trunk and a distinct crown. They had leather-like supple bark and leathery fronds marked with red-and-blue veins. They even had air-filled fruit-like bladders keeping the tops afloat, while the fronds formed underwater networks that some animals used as nests, and some intelligent natives as storage place.
The main seatree forest on the planet was the Mkbuto Seatree Preserve, on the equator, growing for hundreds of kilometers and becoming a main part of the local ecosystem. Mon Calamaris and Quarrens were not prone to settle that place, because it existed over the border of two tectonic places and because it was considered to be sacred.