Agave Deserti (?) is found in most places along the coasts on Costa Blanca. The one on this picture is found on the road between Albir and Altea. It is one out of a large number of agaves, arriving here from the Americas after Columbus made his "rediscovery" of that part of the world.

Many of the agaves are poisenous, causing skin rashes!... but this one seems to be OK.

But then the good news!... at least one species - like the one on this photo - is the source of the liquid from which drinks like "Pulque", "Mezcal" and "Tequila" are made... so now you know why the Spaniards brought this one back to Spain.

The destillate "Tequila" is said only to be made from an agave called "Blue Agave",  (Years ago though,  when I used to frequent Mexico, I was told that Tequila was destilled from Pulque, which may also be produced from Agave Deserti. I do also remember having a bit too much Pulque one night, and had a hangover which still hurts, when I think of it.)

It is known that the Desert Agave was used for food as well by Mexican aborigenes, and the fibreous leaves provided material for clothes, ropes etc. The long flower stalk provided a strong beam when dried, and I have seen it used in the roof construction on several old farms here in Spain.
The Agave Deserti flowers only once, and that is when it  is "mature", at the age of 20-40 years, after which wind and weather toppels the stalk uprooting the dying mother plant. New plants do however develope from the root, and I suppose the toppling of the up to 6m tall stalk also throws the seeds away from the mother plant(?)... away from where new plants generate from the root of the mother plant anyway. 
www.brandulph.net
(NB! I am now - May 2008 - pretty sure of, the one on the large picture, is a blue agave, but mightl return on the topic! :o)
Lots of info about the "Agave" is found on this page
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