During our mild winters, I like to have lunch at a local restaurant that provides outdoor seating. Mesquite, Palo Verde and Palo Brea trees, as well as several different species of Agave and other xeriscape plants surround the place. Several of the Agave americana plants are currently in the process of sending up fat flower stalks that look like a giant asparagus. Agave americana flower stalks grow rapidly, at the rate of about two feet per week, until they reach 30 feet high. Since I visit the restaurant once a week, the growth is obvious from week to week. Yesterday I snapped this cell phone photo of the Agave inflorescence that I’ve been watching over the past couple of months. As you can see, the inflorescence is now about 25 feet tall, almost as high as the crown of the Mesquite tree.
Agaves usually don’t flower until they are from eight to 25 years old, depending on the species. They spend those years before flowering storing up energy to send up the huge flower stalk. The flowers last about two months and then the exhausted Agave dies. Offsets replace the original plant. A few species don’t die after flowering, but the majority of the species do.
Agave plants have three types of flower stalks depending on species. One type is the raceme, or an inflorescence having stalked flowers arranged singly along an elongated unbranched axis. Another is a spikate inflorescence where the flowers cling to the stalk in pairs or clusters. The third, like the one in the photo, is the paniculate inflorescence where the flowers appear in clusters on lateral branches, like a candelabra. Some Agave species, such as the Octopus Agave, have a spike with bubils, which are tiny plantlets that fall from the spike and take root. Agave plants will hybridize, so sometimes a plant that normally has one type of flower stalk may have another instead.
By the time it gets too warm to be dining alfresco, the pictured Agave will have completed its lifecycle. Rather than let the offsets replace it, a landscape crew will come in with a mature replacement plant and the whole process will begin again.