In mushroom farming, spawn is a carrier material, usually sterilized grain or sawdust, fully colonized by fungal mycelium. It acts as the seed to inoculate bulk substrates like compost or straw. In historic horticulture, the term also refers to the spreading underground runners or offsets produced by certain perennial plants that can be separated for propagation.
Heard on the job
We inoculated the pasteurized straw bags with five pounds of oyster mushroom grain spawn this morning.