(n) any of various western American plants of the genus Grindelia having resinous leaves and stems formerly used medicinally; often poisonous to livestock, Syn. gum plant, tarweed, rosinweed
n. (Bot.) A name given to several resinous-glandular composite plants of California, esp. to the species of Grindelia, Hemizonia, and Madia. [ 1913 Webster ]