Botanists call the Century plant an agave. There are different species in the Southwestern US/Mexico and also on the Canary islands. Don described them very well.
Some of them are used commercially: Out of the fermented sap of the Blue agave (Agava tequilana) in Mexico e.g. you can distill (you guessed it!) Tequila! aussie
Russ, I think the stalk of the big agave flowers is much higher and quite different from the cluster of yucca blossoms. See the two added pictures: The first pic shows a blossoming agave, the second double pic shows two different yucca species which can be found in Southern California. (Also the agave leaves are much thicker than the yucca leaves.)
So Chris can decide if he has seen agaves or yuccas is Sou CA.
Now - has anybody a good idea how to model such a plant?
Ron