melanocyte-stimulating hormone: a hormone secreted by the anterior pituitary gland that controls the degree of pigmentation in melanocytes
hormone: the secretion of an endocrine gland that is transmitted by the blood to the tissue on which it has a specific effect
aphyllanthes: one species; small fibrous-rooted perennial with rushlike foliage and deep blue flowers; sometimes placed in its own family Aphyllanthaceae