Arboretum Index Pages Home


OAK, BUR (Quercus macrocarpa) B-10,B-13

This tree is large and pyramidal that grows 70-80’ high. The dark-gray bark is rough and develops deep ridges and a corky appearance. The simple leaves are dark green in summer and change to a dull yellow in the fall. The fruit is an acorn that is stalked, 3/4-1 1/2” long with a downy apex. Native: Nova Scotia to Pennsylvania and west to Manitoba and Texas.

OAK, CRIMSON SPIRE (Quercus robur x Q. alba 'Crimschmidt') B-14

This tree is a hybrid of the White and English Oaks. From the White Oak comes dark green foliage that is mildew resistant. From the English Oak comes the upright columnar growth habit. Mature height is 45'. Fall foliage is a rusty red. From the J. Frank Schmidt & Son Nursery in Oregon.

OAK, GAMBEL (Quercus gambelii) H-11

This oak was named after William Gambel who collected it in the southern Rockies. It is also referred to as the Utah White Oak. Its deeply lobed leaves are green and turn yellow, orange, and red in the autumn. It is often only a tall shrub or small tree bearing acorns in the fall. Native: Mountains of the southwestern United States and far northern Mexico.

OAK, RED (Quercus rubra) B-15

This fast-growing oak can reach heights of 60-75' at maturity. The bark becomes brown to black as the tree ages, with gray ridges and shallow fissures. The leaves have 7-11 lobes and are lustrous dark green above and pale yellow, white, or gray underneath. Fall foliage is red. The acorns are 3/4-1" long. This is a good tree for lawns, parks, and streets. Native: Nova Scotia to Pennsylvania and west to Minnesota and Iowa.

OAK, SWAMP WHITE (Quercus bicolor) B-4

This round-top tree grows 50-60’ in height. The short trunk has grayish-brown bark divided by deep fissures and long, flat ridges. The leaves are glossy green above with pale, feltish undersides. They change to yellow in the fall. The acorn is 1” long. Native: Quebec to Georgia and west to Michigan and Arkansas.

OAK, UPRIGHT ENGLISH (Quercus robur ‘Fastigiata’) B-1

This tree is distinctly upright and columnar in habit. A mature tree may be 50-60’ in height, but only 10-15’ wide. Leaves are shiny, dark green on the top and pale blue green underneath. The leaves have six to fourteen rounded lobes. The oval, yellow-green acorns are on long stalks with only 1/3 of the nut enclosed by the cap. Native: Europe, north Africa, and western Asia.

OREGON GRAPEHOLLY (Mahonia aquilfolium) H-5,J-6,J-8

Evergreen shrub with upright, heavy stems and an irregular and open habit. The leaves open with a reddish bronze color, changing to a light, glossy yellow-green and finally lustrous dark green in summer. Fall color is purplish bronze. Spring flowers are bright yellow and produced a blue-black berry with a whitish bloom. Native: British Columbia to Oregon.

OSAGE-ORANGE (Maclura pomifera) C-4

This 20-40’ tree seems to thrive almost anywhere. Sharp thorns on young branches account for its popularity as a hedge. Leaves are glossy, medium green, pointed ovals that turn yellow before dropping in autumn. In warm to hot summer regions, when trees of both sexes are in the same garden, the females will produce 4-5” inedible fruits that resemble bumpy, green oranges. A yellow dye is extracted from the roots and bark. The rot-resistant wood was used by Indians for bows. Thus, another common name is the Bow-wood or Bois D’Arc. Native: Arkansas to Oklahoma and Texas.

Back to the Top of the Page