September 7th 2023
A Tale of Two Parasites
Turning from the trunk to the roots of the beech trees, one can find another, much friendlier parasite. Beechdrops (Epifagus virginiana) are rather unremarkable at first glance – mistakeable for a simple fallen twig. However, their appearances are quite deceiving. Beechdrops are an extraordinary species found only on beech roots of eastern North America.
Beechdrops are a non-photosynthetic plant that has evolved to get all its nutrients from the root systems of beech tree stands. Rather than getting from the sun like most plants, beechdrops send out specialized structures that puncture beech tree roots and syphon energy from them. This kind of root parasite can sometimes become pathogenic and cause damage or even mortality to the host tree. Thankfully, beechdrops only flower for one season after reaching maturity. They don't stick around long enough to cause lasting harm to their host.
The humble beechdrop is a short-lived, benign cohabitant for an American beech tree. It's like a summer subletter you tolerate but don't care for. For forest managers and researchers, however, it is a wonderfully useful species.
By themselves, beech trees are slow-growing; they take a long time to colonize new environments and grow into mature, healthy forests. Beechdrops take even longer since they can only establish once dense beech root networks are already running through the soil. Because of this long establishing time, scientists use beechdrops as an indicator species for overall forest health. They can only be found in forests, like those on Mont Saint-Hilaire, that have not been recently harmed by intensive human activity.
The future of our forests
As beechdrops and beech bark disease demonstrate, not all parasites are created equal. One of the species presented above (beech scale insects) is a horrible pathogen for American beech trees and the ecosystems and people reliant on them. Meanwhile, the other species (beechdrops) is harmless to the tree and beneficial for research and conservation management.
Beech bark disease, compounded by other environmental pressures, seriously threatens our forests. Beechdrops, however, are a sign of hope that we have not yet lost the fight to save our ecosystems.
Field Operations Assistant
Gault Nature Reserve of McGill University
- Invasive Species Center. Beech Bark Disease. Invasive Species Centre (blog), 2023.
- Barbara K Andreas, John J Mack, and James S McCormac, “Floristic Quality Assessment Index (FQAI) for Vascular Plants and Mosses for the State of Ohio” (Ohio Environmental Protection Agency, Division of Surface Water, Wetland Ecology Group, 2004).
- Yi-Hsin Erica Tsai and Paul S. Manos. Host Density Drives the Postglacial Migration of the Tree Parasite, Epifagus Virginiana. Proceedings of the National Academy of Sciences of the United States of America 107, no. 39 (September 28, 2010): 17035–40.
- Jessica Turgeon. The Relationship Between Beech Tree Size and Beech Drop Density. The St. Lawrence Lowlands (blog), November 22, 2019.
- Impact of Leaf Litter of Different Tree Species on Soil Chemistry and Biodiversity. CORDIS | European Commission, April 9, 2021.
- American Beech | Ontario.ca, accessed on August 15, 2023.