Several cacti.
A cactus is a type of Earth plant found in the western frontier of the United States of America.
In recalling his late 19th century history of the Ancient West, Pavel Chekov noted that "all western cossacks had were poisonous snakes and cactus plants." (TOS: "Spectre of the Gun")
Vina believed that all of Mojave was once covered with cactus and blowing sand. (TOS: "The Cage")
Ard'rian McKenzie kept several cacti in her home on Tau Cygna V. (TNG: "The Ensigns of Command")
Alien varieties of cactus include the Cyprion cactus and Torothan cactus. (TNG: "Genesis"; ENT: "Desert Crossing")