Sentence:  In order to establish itself in any locality a plant must hold its own against competitors which, masters of the soil from time immemorial, have been selected to fit the soil and climate. Moreover, emmer is not cultivated anywhere in Palestine. This wild wheat is furthermore a different plant from any known in cultivation, a <WSD>polymorphous</WSD> race, no doubt, but a distinct one. 
Meaning of the word marked with <WSD> tags:  Having, or occurring in, several distinct forms