presented his classical notes on Agave to the academy thirty-five years ago, he stated that the occurrence on the margins of these leaves of detaching threads above and little prickles below was, so far as known, unique in the genus, and except for a very few close relatives of this plant the statement still holds true.
The main kinds of Agave fall into two recognized classes: one, illustrated by the true century plant and the pulque magueys, bears flowers in candelabrum-like panicles; the other, like the lechuguilla, has its flowers disposed mostly in pairs along a wand-like spike. An effort has been made to separate these latter from Agave under the generic name Littæa, but this has not met with general acceptance and in fact there are puzzlingly intermediate species, as, for instance, the Littæa
