Quercus engelmannii is a small tree growing to 10 metres (33 feet) tall, generally evergreen, but may be drought-deciduous during the hot, dry local summers, and has a rounded or elliptical canopy. The bark is thick, furrowed, and light gray-brown. The leaves are leathery, 3–6 centimetres (1+1⁄4–2+1⁄4 inches) long and 1–2 cm (1⁄2–3⁄4 in) broad, of a blue-green color, and may be flat or wavy, with smooth margins. The flowers are catkins; the fruit is an acorn 1.5–2.5 cm (1⁄2–1 in) long, maturing 6–8 months after pollination.[5]
The wood is dark brown and strong, but tends to warp and split upon drying, and is of low value as timber.
Fossil evidence shows that Engelmann oaks once had a wider range, extending through what is now the Mojave and Sonoran deserts into eastern California and Arizona. The Engelmann oak is most closely related to the Arizona white oak(Q. arizonica) and Arizona blue oak(Q. oblongifolia), which are native to the subtropical pine-oak woodlands of Arizona and northern Mexico. The Engelmann oak is considered to be the northernmost species of subtropical oak, which was isolated from its closest relatives to the east by the drying of the southwestern deserts.
^Tucker, John M. (1993). "Quercus engelmannii". In Hickman, James C. (ed.). The Jepson Manual: Higher Plants of California. University and Jepson Herbaria.
