This was once a common tree, but in recent years its population has been devastated by Sudden Oak Death, an invasive plant pathogen. This may be shrubby and many-stemmed, but is often a tall, single-trunked tree. It has distinctive leaves, evergreen, simple, alternate, ovate to oblong, 3–14 cm long. The leaves have margins that are either entire or serrated, and an obtuse tip. The tree is monoecious, the tiny white male flowers in more or less erect catkin-like spikes, and the inconspicuous female flowers below the male. Like most black oaks, the acorns mature over two years. The acorns are distinctive, the cup having a soft-spiny appearance, the result of very slender, spreading to reflexed scales. This is quite different from the appressed scales found in true oaks.