Botanical name: Quercus macrocarpa
Family: Fagaceae (beech)
Group: White Oak

Click on images of Bur Oak to enlarge.

A.K.A. mossy-overcup oak, mossycup oak, white oak, blue oak and scrub oak.

• Native
• Deciduous
• The second part of the scientific name or specific epithet, macrocarpa means large seed or fruit and the bur oak produces the largest acorns (up to 2 inches in diameter) of all the oaks found in North America.
• Fully mature trees can grow massive 8 – 10′ diameter trunks with a huge open crown, that can be as wide as the tree is tall.
• Reaches heights of 70 – 100′ and occasionally more.
• They are slow growing trees, although, when they are young they can grow more than 12 inches a year in height and grow long tap roots  very quickly.
• Lifespan is approximately 400 years.
• Simple leaves are broad and 6 – 10 inches in length with lobed margin.
• Bur oak is monoecious.
• Flowers – Catkins are 4 – 6 inches in length.
• Fruit –  produces acorns every 2-3 years.
• It is drought and fire resistant.
• Bur oaks fair well in urban environments.
• Some damaging insects include oak webworm, oak skeletonizer, oakleaf caterpillar, oak lacebug, redhumped oakworm and June beetles.
• Common problems include: susceptible to (fungi)  Strumella canker, cotton root rot and Oak wilt – sometimes through rare root graphs with red oaks.
• Plant Hardiness Zones 3 – 8

 Photographs of the oldest bur oak in Boulder, Colorado.