By Nina Jungman
Have you ever wondered how air plants obtain nutrients and water to live while they are just hanging out on a tree’s branch? Up to half of tropical forest plant species grow on other plants rather than in the soil, and for them, nutrient uptake looks a little different.
One of the most interesting ways is referred to as the “tank” structure found in some large bromeliads. These tanks are formed by the overlapping bases of the plant’s leaves, trapping water that contains nutrients, which are then absorbed by the plant. This water also hosts complex microbial communities that help process these nutrients. However, it takes years for a bromeliad to grow big enough to form a tank, so how do young bromeliads do it?
Jade Stryker and Elizabeth White, then undergraduate students at New College of Florida, under the advisement of Drs. Brad Oberle (currently at The New York Botanical Garden) and Erika Díaz Almeyda (currently at California State San Marcos) and Dr. Brian Sidoti, director of The Kampong, studied the changes in shape, growth, nitrogen intake, and leaf-surface bacteria of the state-endangered species giant air plant (Tillandsia utriculata) as it grew from a juvenile to an adult capable of forming a tank.
Tillandsia utriculata. Photo credit.
The team found that key transitions happen when the longest leaf reaches between 14 and 19cm in length. Before forming a tank, the plant mainly stores ammonium in its leaves, but after, it switches to absorb more nitrate. The bacteria living on the leaves also change as the plant grows, becoming more diverse once the tank has been established. These specialized bacteria make nitrogen more biologically available and help support tropical plant nutrient uptake.
Tank or not, bromeliads are really interesting and complex plants currently threatened by the Mexican Bromeliad Weevil (Metamasius callizona). Come see and learn about the Florida native bromeliads at the Kampong, and maybe catch one of our interns to talk about our current seed germination and growth rate experiments.
