Some of us peak at 20. For one 80-year-old American agave getting ready to bloom at Matthaei Botanical Gardens, adolescence is just beginning. A variegated American agave (Agave americana) collected in Mexico in 1934 by University of Michigan grad student Alfred Whiting, is sporting a flower stalk that’s growing nearly six inches a day. As of May 22 the stalk was more than 20 feet tall and workers have removed a pane of glass from the conservatory ceiling to allow the stalk to continue its upward climb.
That’s the good news. The bad news, especially for anyone who’s seen this enormous plant in the conservatory or in nature with its sinuous yellow-streaked leaves bristling with spikes, is that the plant will bloom, set seed and die, says Mike Palmer, horticulture manager at Matthaei Botanical Gardens & Nichols Arboretum.

Close up

A view of the flower stalk from below (May 21, 2014)

A view from above—outside the conservatory looking down on the stalk (May 21, 2014)

According to Palmer the American agave usually blooms in nature at 10 to 25 years of age. “Although no one knows for sure what combination of environmental conditions induces flowering,” he says. “And it’s rare for one to bloom indoors. Of course, being in a conservatory helps!” American agave foliage is usually 3 to 6 feet tall and 6 to 10 feet wide. The flower stalk can reach up to 30 feet tall. The American agave is often referred to as the “century plant,” probably because  humans have noticed (and then exaggerated) how long it takes the plant to mature and flower.
Thankfully, life will go on for the Botanical Gardens’ variegated agave, Palmer points out. “While it’s sad that the parent plant will die, it also grows ‘pups’ on the flower stalk and offsets at the base that are identical clones of the original plant,” he says. And it produces hundreds or even thousands of seeds that have the potential to grow. “But in the harsh, low water environment of the desert,” explains Palmer, “plants must produce many offspring to get a few progeny that will reach adulthood.”

Matthaei horticulture manager Mike Palmer stands in front of the agave’s flower stalk. 

The Matthaei Botanical Gardens’ agave is native to the Southwest United States and Mexico and is an example of a plant species that’s well adapted to dry or desert conditions. The American agave is now planted throughout the world as an ornamental in arid regions. It was likely planted in the ground bed of the conservatory on Dixboro Road in the early years of the U-M’s botanical gardens at that location.

The American agave is more than just a pretty flower stalk. If you think the flower spike of the American agave looks like a giant asparagus spear, you’re on to something. The plant is in the asparagus family. And while many know agave as the source of tequila, the fiery distilled beverage is made only from the tequila agave (Agave tequilana). In areas of Mexico where tequila is produced, the American agave is used to make a similar alcoholic drink called mezcal. The flower stalk of the American agave can be cut before flowering to produce aguamiel, a sweet liquid collected at the base of the stalk. This liquid can be fermented to make a drink called pulque. Additionally, fibers gathered from within the leaves are used for making rope or twine.
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