This genera in the Asteraceae or sunflower family is one of the more difficult to pronounce. The name is based on the ancient and honorable appellation of Gutierrez (a Spanish botanist, in this instance), but you would never know that by hearing it bandied about by botanists. You might think it should be Goo-tyAIR-ess-eea, following the principle of simply tacking an “ia” onto a proper name. However, most botanists in our area say “Goot-ur-EEZ-eea,” or “Goot-ur-EET-zia.” Ranchers pronounce it “snakeweed.”
It turns out to be difficult to preserve the regular pronunciation of a proper name in day-to-day use of botanical Latin. A generally accepted rule of thumb is: pronounce it the way you learned it from someone else, but with confidence.