Century Plant Grows Fatally Tall to Survive

The massive century plant is one of the most distinctive plants of the Chihuahuan, a tough, sharp-spined member of the lily family with a dramatic strategy for spreading its seeds. One of the largest agaves, the century plant may persist for 50 years before it reproduces in a single season of fatal extravagance. Normally, the century plant gathers energy through its broad leaves that end in a wicked point. The leaf rosette at the base eventually reaches two or three feet across, the waxy surface of its leaves hoarding moisture and its tough root gathering up every drop of moisture. A waxy coating of hydrocarbons on the huge leaf surface reflects 75 percent of the ultraviolet and near-infrared heat radiation, which slows evaporation, conserves water, and reduces damage when the leaves get dehydrated. After decades of tenacious growth, the century plant will pour all of its energy into growing a single remarkable stalk that can tower 30 feet (9.14 m) above its humble base. The stalk then produces an outpouring of yellow, tubular flowers, creating a strange forest of great stalks that makes a once-inconspicuous hillside bristle with color. Remarkably, the plant puts so much energy into sustaining this single, outlandish flowering stalk that it dies with the fading of the blossoms.

Biologists believe this showy, high-risk reproductive strategy is linked directly to the migrations of bats, the major pollinators of the agave. Biologists note that the agave flowers often smell faintly of rotten meat, which attracts not only many of the small desert flies but also bats. The scent of the flowers peaks between eight and 10 at night, precisely when the nectar-feeding bats are most active. Moreover, the precise mix of nutrients and the design of the flowers seem perfectly adapted to the bats’ needs. It also makes sense that a plant trying to attract the attention of night-flying bats would put the sweet bait of the nectar on a tall stalk easily visible in the darkness and easily accessible for bats that lack the dexterity of a bee or a hummingbird.