Sentence:  <WSD>Oyster mushroom</WSD> is regarded as one of the commercially important edible mushrooms throughout the world. It consists of a number of different species including "Pleurotus ostreatus", "Pleurotus sajor-caju",... The <WSD>oyster mushroom</WSD> is the second most important mushroom in production around the world, accounting for 25% of total world production of cultivated mushrooms. 
Meaning of the word marked with <WSD> tags:  Any of several mushrooms of the genus "Pleurotus" cultivated for food.