Mysterious 'ghost tree' that doesn't need photosynthesis in American forest

The secret to survival without photosynthesis of the albino "ghost tree" species in the forests of California, USA, has been a big question for scientists for a century.

An albino rosewood tree in the California forest. Photo: Outside Online.

An albino rosewood tree in a coastal forest in California, USA, has been dubbed the “ghost tree” because of the distinctive color of its trunk. The tree lacks chlorophyll, the green pigment that allows it to photosynthesize from sunlight. “It should be dead, but it exists like a ghost,” said biologist Zane Moore, a PhD student at the University of California, Davis.

The mystery of the albino rosewood has puzzled researchers for more than a century. The trees are so elusive that, unless you look closely, you might doubt they really exist. But Moore believes there is a scientific explanation for the existence of the tree and the entire forest.

Until recently, almost no scientists had been able to study albino rosewood trees. Albinos are extremely rare. According to Moore’s latest records, the number of albino trees in the world is only 406. The tree’s genome has 32 billion base pairs compared to 3.2 billion in humans, and each chromosome has six copies instead of two. Researchers have not been able to sequence the rosewood genome and have not yet found the mutation that causes the tree to become albino.

Rosewood trees can clone themselves. Layers of plants in close proximity communicate through their roots. During the harsh winter and early spring months, they share nutrients equally. Scientists applied dye to trees at one end of a grove and watched the dye spread through the root network to the other end.

This partnership only lasts until summer. After that, each tree, branch, leaf, and bud must survive on its own. Trees that cannot photosynthesize are removed from the nutrient-sharing system through their roots and die in the fall. Moore has learned how albino rosewoods benefit from the system by siphoning off sugars produced by healthy trees around them. “Many people think albino rosewoods are parasitic and even call them ‘vampire trees,’ but rosewoods are smarter than that,” Moore says.

Moore and fellow arborist Tom Stapleton decided to document the location of every albino rosewood they found. Their maps showed that albino trees often grow in less favorable conditions and environmental stresses that can trigger mutations. Moore then set out to collect specimens from albino trees and healthy neighbors along the California coast.

Moore found that the leaves of the albino trees were filled with a mixture of cadmium, copper, and nickel. On average, each white needle contained twice as much of the toxic heavy metal as a green needle on a normal tree. Moore believes the problem lies in the stomata, the hollow spaces that allow trees to absorb water. Trees that are dehydrated quickly are forced to take in more water, meaning that albino trees have twice as much heavy metal-laden water flowing through their trunks as healthy trees.

“It seems like the albino plants are sucking up heavy metals from the soil. They’re poisoning themselves,” Moore said.

Moore tested the most toxic albino rosewood trees, which had 10 times more nickel in their leaves than healthy trees. In a paper due to be published next year, Moore says albino rosewoods have a symbiotic relationship with other rosewoods. They act as a storehouse for the poison in exchange for the sugars they need to survive.

Moore plans to study this phenomenon further. His next experiment involves injecting nickel into green and albino rosewood plants grown in the lab to see if the plants growing alongside the albino ones grow healthier. He also wants to test whether the heavy metals in the albino plants stay in the plants or seep back into the soil. If his theory proves correct, Moore hopes to plant albino rosewoods in polluted areas in the future to make the soil safer for other plants.

According to VNE