New research suggests that mistletoe, the plant that encourages kissing at Christmas, is actually a parasite and has an unusual feeding strategy.
Like other plants, mistletoe can use sunlight to create its own food, but it prefers to siphon water and nutrients from other trees and shrubs, using false roots to invade its hosts, according to a new study.
University of California Riverside plant-insect ecologist Paul Nabity said: "Plants are autotrophic, they make their own food. Humans are heterotrophic, we eat it.
"Mistletoe are mostly heterotrophic, but they can switch if they want to."
He added: "They seem to know when they're attacking the same host, and can reduce the virulence of their attack."
Researchers examined a native species of mistletoe found throughout the Sonoran and Mojave deserts that often grows on acacia, palo verde or mesquite trees.
When they removed one of two mistletoes from a branch, they found the plant left behind did not increase its photosynthesis. In some cases it reduced its water intake, according to the paper published in Current Biology.
Researchers say communication among mistletoes is possible through a variety of methods.
But Dr Nabity said that however mistletoe communicates, it doesn’t necessarily need to be removed from infected trees.
"Don’t remove mistletoe because you think they’re all bad," he said