An 80-year-old American agave plant that will flower once then die seems poised to do just that.
Housed at the University of the Michigan since 1934, the plant has grown so rapidly since the spring that at more than 27 feet (8.2 metres) it is now too tall for the Ann Arbor conservatory, which has had to remove a pane of glass to accommodate it.
Just this week, one of the asparagus cousin's flower buds took on an orange-like blush. Could that mean the buds are ready to finally bloom?
"We've been guessing and speculating about when this particular agave is going to bloom for weeks and have been proven wrong every time," said Joe Mooney, spokesman for Matthaei Botanical Gardens and Nichols Arboretum.
The agave began to shoot upward in April, at which point a volunteer pointed out a flower stalk to Matthaei horticulture manager Mike Palmer.
Since then, it has grown as much as 6 inches (15 centimetres) a day. Palmer called the pre-branching version of the plant "a giant asparagus on steroids."
The variegated American agave (Agave americana) was collected in Mexico by famed ethno-botanist Alfred Whiting, who then was a University of Michigan graduate student. Known as the century plant because it blooms infrequently, it is native to Mexico and the American Southwest and typically lives 10 to 25 years in the wild before blooming a single time then dying.
It's a mystery why this particular agave stuck around for eight decades, Palmer said.
"We don't know why it waited so long," he said.
While many know agave as the source of tequila, that particular beverage is made from the tequila agave (Agave tequilana). In areas of Mexico where tequila is not produced, the American agave is used to make a similar alcoholic drink called mezcal. The American agave's fibres also can be gathered from within the leaves and used for making rope or twine.
Once the flower blooms it will take many months before the plant dies. But in the plant's final throes, it is expected to produce "pups," or genetic clones that look the same as the parent plant, from which Matthaei officials can propagate the species.
"If we can get even one pup, we'll plant it," Mooney said.