4 differnce betwen prothallus and protonema ?

Prothallus

Protonema

It is the gametophyte of pterydophytes like fern.

It is the first stage of development in moss plants.

It has a heart like shape with numerous rhizoids and sex organs antheridium (male) and archegonium (female).

It is a thread like chain of cells.

It is formed from already germinated spore.

It is formed directly by the germination of spores.

Prothallus develops further to give rise to sperms and ova.

Protonema develops into gametophyte.