''Ostrya knowltonii'' is a species of

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...

known by the common names Knowlton's hophornbeam, western hophornbeam, woolly hophornbeam, and wolf hophornbeam. It is also one of many trees called

ironwood Ironwood is a common name for many woods that have a reputation for hardness, or specifically a wood density that is denser than water (approximately 1000 kg/m3, or 62 pounds per cubic foot), although usage of the name ironwood in English ma ...

. It is native to

Utah Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...

Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...

New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...

, and

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

in the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

, but its distribution is localized and sporadic. This plant is a tree that grows to 9 to 12 m in maximum height. The trunk is short and it divides into many crooked branches. The crown is rounded. The bark is brownish gray and furrowed into scales or strips. The leaves are up to 6.3 cm long and have serrated edges. Male and female flowers are borne in separate

catkin A catkin or ament is a slim, cylindrical flower cluster (a spike), with inconspicuous or no petals, usually wind- pollinated ( anemophilous) but sometimes insect-pollinated (as in '' Salix''). It contains many, usually unisexual flowers, arra ...

s, the male up to 3 cm long and the female up to one. The fruit is a nutlet. This plant grows in the American Southwest, including the rims of the

Grand Canyon The Grand Canyon is a steep-sided canyon carved by the Colorado River in Arizona, United States. The Grand Canyon is long, up to wide and attains a depth of over a mile (). The canyon and adjacent rim are contained within Grand Canyon Nati ...

. It grows in oak woodlands, pinyon-juniper woodlands, and

Ponderosa pine ''Pinus ponderosa'', commonly known as the ponderosa pine, bull pine, blackjack pine, western yellow-pine, or filipinus pine, is a very large pine tree species of variable habitat native to mountainous regions of western North America. It is t ...

forests. It occurs in sunny, dry locations. The wood of the tree is hard and tough, and it can be used to make durable items such as fence posts and tool handles.

References

{{Taxonbar, from=Q4498408 knowltonii Trees of Northern America Plants described in 1894