Any of various large agaves of Mexico and the southern US, especially the American aloe, Agave americana.
2006, Thomas Pynchon, Against the Day, Vintage 2007, p. 424:
through black fields, where tlachiqueros brought sheepskins slung across their backs full of fresh maguey juice to be fermented, and campesinos in white lined the right-of-way
1985, Cormac McCarthy, Blood Meridian, Vintage 1992, p. 147:
and they rode through strange forests of maguey--the aloe or century plant--with immense flowering stalks that rose forty feet into the desert air.