Polyporus umbellatus is a medicinal mushroom used in traditional Chinese medicine for treating water retention and swelling. This study found that the type of symbiotic fungus (Armillaria species) growing with the mushroom significantly affects both how much mushroom is produced and the amounts of beneficial compounds it contains. Among three Armillaria species tested, A. gallica produced mushrooms with the highest yields and the most polysaccharides, making it the best choice for cultivation.