— prothallial, prothallic, prothalline /proh thal"een, -uyn/ , adj. — prothalloid , adj.
/proh thal"ee euhm/ , n. , pl. prothallia /-thal"ee euh/ .
1. Bot. the gametophyte of ferns and related plants.
2. the analogous rudimentary gametophyte of seed-bearing plants.
[ 1855-60; pro- PRO- 2 + thallíon, dim. of thallós young shoot; see -IUM ]