The family is Liliaceae (formerly Amaryllidaceae), but order (according to the Linnaean scheme) uses the suffix -ales, never -aceae. The order for Liliaceae is Liliales. Also, the species epithet (the second word in binomial nomenclature, redundant i know) is not capitalized. So the botanical name for the century plant should be A. americana. Also, as a rule species names and other taxonomic language is set apart from normal language by italics or capitalizing all the letters.
The century plant was so named because, like many other
xeric plants, it grows slowly and flowers infrequently. This is why you won't see century plants dominating anything but the most extreme, xeric lands because they grow too slowly to
compete with other plants.
Not to be confused with
desert ephemerals which grow quickly, reproduce quickly, and die soon after.