Sentence:  <WSD>Oyster mushrooms</WSD> (Fig. 4.1) are the most suitable fungal organisms for producing protein-rich food from various agro-wastes without composting...."Pleorotus" mushrooms irrespective of the particular species are generally referred to as "oyster mushrooms". 
Meaning of the word marked with <WSD> tags:  Any of several mushrooms of the genus "Pleurotus" cultivated for food.