myrtle: widely cultivated as a groundcover for its dark green shiny leaves and usually blue-violet flowers
periwinkle: chiefly trailing poisonous plants with blue flowers
mucus: protective secretion of the mucus membranes; in the gut it lubricates the passage of food and protects the epithelial cells; in the nose and throat and lungs it can make it difficult for bacteria to penetrate the body through the epithelium