Mystery Plant: Member of Fagaceae family is relative of American chestnut

The American chestnut (Castanea dentata) is a tree that shall for evermore be immortalized as a true forest giant of the eastern United States, often up to 100 feet tall and frequently with a trunk diameter of greater than four feet.

It is a species that utterly dominated forest ecosystems in both the mountains and piedmont and represented the most commercially important hardwood species, highly prized for its valuable lumber.

It is somewhat fancifully suggested that at one time long ago, before the onslaught of European settlers, a squirrel would have been able to run from Maryland to northern Alabama along the branches of American chestnuts, due to their great abundance — which of course is perhaps stretching it a bit.

Sadly, these mighty giants have essentially vanished, having fallen away due to an introduced fungal disease known as “chestnut blight.” Occasionally in the forests you can now find sprouts of American chestnut, but they never (or rarely) attain much size, certainly not large enough to develop fruits.

Chestnuts belong to the family named Fagaceae. As with all plant families, this one was named after one if its constituent genera, in this case, the genus Fagus. Fagus is a genus containing about 10 different species and, of course, the one we are most familiar with is Fagus grandifolia, the American beech.

All of the oaks belong to the family Fagaceae as well and all oak species are maintained within the genus Quercus. All of this is just to point out that a plant family, in this case, the Fagaceae, is typically made up of several different but related genera. Some plant families, though, will contain only a single genus.

This family is roundly known as, and referred to as, the “oak family.”

Now, this week’s mystery plant is a member of the family Fagaceae, and a member of the genus Castanea. It is a relative of the American chestnut — a relative that seems to be mostly impervious to the deadly fungus mentioned above.

It is a small tree, usually not more than about 20 feet tall, with characteristic sharply saw-toothed leaves. In the autumn the leaves turn brown — not too showy — and remain attached to the branches a good while.

This plant is not native to North America. It is from China and has been introduced, on purpose, for wildlife food, and more commonly for most people, as a street tree. As with all chestnuts, the flowers are tiny and inconspicuous, without any petals. Separate male flowers and female flowers occur on the same plant.

The male flowers occur in a very slender, string-like spike, with or very near the female flowers. If all goes well, each female flower will be able to produce a hard, shiny, brown, sweet nut about an inch long, held tightly in a bright green, very spiny (ouch!) bur.

The burs eventually open up in the fall, releasing the sweet nuts, beautifully shiny and brown. They are quite good for people to eat, too, but the nuts themselves are small and hard to harvest. You probably won’t be seeing them in the supermarket.

(Answer: “Chinese chestnut,” Castanea mollissima)