annulus: (Fungi) a remnant of the partial veil that in mature mushrooms surrounds the stem like a collar
plant part: any part of a plant or fungus
vasopressin: hormone secreted by the posterior pituitary gland (trade name Pitressin) and also by nerve endings in the hypothalamus; affects blood pressure by stimulating capillary muscles and reduces urine flow by affecting reabsorption of water by kidney tubules