subscribe to RSS feed

Carbon tax on beech trees!

by William (Ned) Friedman, Director of the Arnold Arboretum
October 1, 2018

Beech drops

Carbon tax on beech trees!

A serendipitous encounter with a magnificent population of beech-drops on Peters Hill has really made my week. Beech-drops (Epifagus virginiana) is a flowering plant whose ancestors lost the ability to photosynthesize. It obtains all of its organic carbon by invading the fine roots of American beech trees (Fagus grandifolia). Not a touch of green can be found on these plants. What I saw under a small thicket of beeches on Peters Hill were hundreds (if not thousands) of inflorescences (upper left) emerging from the leaf duff, with their wonderful purple flowers (upper right) and developing fruits. It was amazing.

Beech drops

I excavated a couple of conjoined individuals and brought them home, where I washed the soil off the below ground bases of the plants (lower left). The bulbous structure, referred to as a tubercle, is a storage organ for the carbon that is stolen from the beech tree root. Several inflorescences develop from the tubercle, as well as small stubby roots that do not absorb water (beech-drops steal water from the beech tree), but anchor the plant in the soil.

Beech-drops seeds are miniscule (lower right, on tip of my index finger), with estimates of as many as four million seeds in a pound. There is barely enough food (energy) in a seed to get the embryo out the door in the spring. But, if a beech-drops seed detects the chemical profile of a beech tree root nearby (millimeters), out pops a root which then burrows into the beech tree root and hooks up the plumbing to steal water (from the xylem) and sugars (from the phloem). Brilliant stuff!

Leave a Reply

Your email address will not be published. Required fields are marked *