Yes, THALLOPHYTE is a Scrabble word!

Letter values in Scrabble US: T 1, H 4, A 1, L 1, L 1, O 1, P 3, H 4, Y 4, T 1, E 1.

Is it a valid word?

THALLOPHYTE is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

any of a group of cryptogamic organisms consisting principally of a thallus and thus showing no differentiation into stem and root and leaf