wood aster: any of several asters of eastern North America usually growing in woods
aster: any of various chiefly fall-blooming herbs of the genus Aster with showy daisylike flowers
releasing hormone: any of several hormones produced in the hypothalamus and carried by a vein to the anterior pituitary gland where they stimulate the release of anterior pituitary hormones; each of these hormones causes the anterior pituitary to secrete a specific hormone