Bur Oak, Quercus macrocarpa: Majestic tree
Description: Bur Oak, Quercus macrocarpa, also called Mossycup Oak and Prairie Oak, is native to tallgrass prairies and river bottomlands in the Blackland Prairie & Cross Timbers regions of North Texas. Bur Oak averages 70 ft tall and 70 ft wide, but can grow to over 100 ft tall and 100 ft wide. It has deeply furrowed, dark gray bark and multi-lobed deep-green leaves of 8 inches to 1 foot in length and up to 6 inches wide. Bur Oak is deciduous; its leaves turn yellow in autumn and completely shed in winter. New growth appears in early spring.
Flowers and Seeds: Bur Oak's common and species names refer to its large acorns. "Bur" refers to the acorn cup that looks like the fringed bur of a chestnut, while “macrocarpa” means large-fruited. Bur Oak’s impressive acorns are as big as 2 inches in diameter, with a fringed cap. The acorns mature in late summer or early fall, following pollination of catkin type flowers in spring.
Planting sites: Bur Oak should be planted where it will have room to grow. It will grow in various soil types, especially deeper soils. It should be planted in full or part sun.
Watering Instructions: During dry spells, Bur Oak should have supplemental water for the first 2-3 years after it is planted. After that, it will appreciate supplemental water during dry periods, but it is drought tolerant.
Comments: Bur Oak is fast-growing for an oak, usually gaining a foot or more of new growth each year. It is also long-lived, with some individuals living 200 years. Bur Oaks are heat-, cold-, drought-, air-pollution- and car-exhaust-tolerant and resistant to most pests, including oak wilt. Bur Oaks have deep tap roots and don’t put out above-ground roots that damage sidewalks or slab foundations. No pre-treatment is necessary to propagate new trees from acorns gathered in the fall. Fresh Bur Oak acorns should be planted outdoors or in deep containers to accommodate the initial deep taproot. Keep pots protected from squirrels and rodents who will dig and eat the planted acorns. Bur Oaks provide shelter and nesting sites for birds, food for mammals and is the larval host food for Edwards Hairstreak and Horace’s Duskywing butterflies. Consider planting Bur Oaks instead of non-native trees like the invasive Chinese Pistache or short-lived Silver Maple. Bur Oak is an excellent shade tree for North Texas.
Written by Dr. Becca Dickstein