Trees & Shrubs of the Eloise Butler Wildflower Garden

Hophornbeam is a slow growing tree of medium height (20 to 50 feet), usually never more than one foot in diameter, with a tapering crown.

Leaves are alternate, oval or elliptical with a distinctive double sawtooth edge. Surfaces are smooth but there is fuzziness along the mid-vein and on the stalk (Petiole). The leaf tip is pointed, usually abruptly so. In Minnesota's climate dry brown leaves tend to stay on parts of the tree into the winter months.

Bark is grayish-brown with vertical strips that usually have a slight spiral twist off the vertical. These strips flake off easily. Young stems will be smoother with a reddish brown color.

Twigs are reddish brown, varying from having some fine hair to mostly smooth, with plump buds that have about 6 grooved scales. Bud scales have a darker band near the scale margins.

Flowers: Flowers are separate (monoecious). Female flowers (pistillate) are light-green and catkin-like, about 1/2 inch long with protruding reddish styles. The female flowers develop at the tip of the prior years wood, just as the leaf buds are opening. Male flowers (staminate) are reddish-green catkins at the end of different branches of the prior years wood, usually in hanging clusters of three. Small green bracts are at the base of the catkin. These male catkins actually develop in the fall, overwinter, and then enlarge in the spring. Catkins are also referred to as 'aments'.

The fruit develops in a white to yellowish hanging cluster of small sacs, inflated at first and then maturing to a flattened brown cluster of sacs, each sac containing a small brown nutlet that has a fine surface reticulation. These clusters may persist through the winter. Trees are usually 25 years old before bearing significant fruit.

 

Habitat: Hophornbeam will grow in partial shade but not dry soils. It is usually found as an understory tree at the edges of woods where it leans to reach sunlight. In the open, it will develop into a nice rounded tree. Young trees do not produce fruit. Seeds require lengthy stratification to break their double dormancy.

Names: The common name of Hophornbeam derives from the seed capsules resembling hops and the wood being as hard as the Hornbeam. The Ironwood name is from the hardness of the wood as anyone who has used an ax on it will acknowledge. The common name 'ironwood' however, is applied to many different tree species that have dense hard wood, in this genus and in others. There are several different species in the Ostrya genus, and unfortunately, all with some use of "Hophornbeam" in their common name. That's why scientific names are best used. As to the name 'Leverwood', Michaux explains in the notes at the bottom of the page. The genus name, Ostrya, is from the Greek word for this tree - ostrys. The species name, virginiana, means 'of Virginia' the state named for England's Queen Elizabeth I, and where the tree was first classified.

The author names for the plant classification are as follows: First to publish was ‘Mill.’ which refers to Philip Miller, Scottish botanist (1691-1771) who was chief gardener at the Chelsea Physic Garden and wrote The Gardener's Dictionary which ran through 8 editions. He was considered “the accurate Miller,” the most famous gardener and nurseryman of the day. The book spread the idea of gardening among the middle class who could now enjoy what was formerly the province of the wealthy. His prime source for North American plants was John Bartram. Miller's work was amended by ‘K.Koch’ who was Karl Heinrich Emil Koch (1809-1879), German botanist, Professor of Botany, first professional horticultural officer in Germany, plant collector in and near Asia Minor.

In earlier years this species was classified as Carpinus virginiana

Comparisons: There are similarities in leaf and catkins with Muscle-wood (American Hornbeam, Carpinus caroliniana), but that tree has smooth bark and the fruit is developed in a cluster of large bracts, rather than in inflated sacs. During the winter, many species in the Birch family have the new male catkins at the tips of the twigs, but the bark of O. virginiana is distinctive.