Of, resembling, or constituting a thallus.(adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "thalloid" in a sentence
"The familiar duckweed which covers the surface of a pond consists of a tiny green "thalloid" shoot, one, that is, which shows no distinction of parts -- stem and leaf, and a simple root growing vertically downwards into the water."
"In thalloid forms fimbriate or lobed margins or outgrowths from the surface lead to the same result."
"In thalloid forms the sexual organs are often sunk in depressions, while in the foliose forms protection is afforded by the surrounding leaves."