Quercus macrocarpa (Burr Oak or Mossycup Oak)


Michael's Opinion

It has the largest acorns of all native oaks. The acorns become an important source of food to wildlife. It grows slowly on dry uplands and sandy plains but is also found on fertile limestone soils and moist bottomlands in mixture with other hardwoods, the most drought resistant of the oaks. The ease with which burr oak can be grown makes it a fine tree for streets or lawns.

Botanical Information

FamilyFagaceae
GenusQuercus
Speciesmacrocarpa
CategoryWoody
TypeTree (deciduous)
OriginCanada and United States of America.
Pronunciation

Details

USDA Hardiness Zone3 - 8
USDA Hardiness Ref.
Canadian Hardiness Zone1a - 8a
Canada Hardiness Ref.
RHS Hardiness ZoneH7 - H4
RHS Hardiness Ref.
Temperature (°C)(-37)-(-7)
Temperature (°F)(-35) - 20
Height20-25 m
Spread18-20 m
GrowthSlow
Flowering PeriodApril

Description and Growing Information

General DescriptionWell adapted for long term survival, strong wood typical of white oak group, thick bark, deep roots and unusually large acorns. This species has been placed on the IUCN Red List as least concern.
ID CharacteristicBark on lower trunks have thick, vertical flattened ridges. The tree often stands alone in fields in the wild, displaying its massive trunk and huge spreading limbs from a distance.
ShapeUpright oval growth habit in youth, becoming rounded, spreading and massive with age.
PropagationSeed is recalcitrant so no treatment is required, 30-60 days at 5°C in moist sand or peat is suggested.
CultivationAdoptable to most types of soils, difficult to transplant, tolerant of city conditions and a great ornamental tree.
PestsNo serious diseases, but oak wilt could possibly be an occasional major concern.
Notable SpecimensNiagara Parks Botanical Gardens, Niagara Falls, Ontario.
HabitatGrows slowly on dry uplands and sandy plains, but is also found on fertile moist limestone soils.
Bark/Stem DescriptionRough, deep ridged and furrowed character, usually dark gray to gray brown in colour.
Flower/Leaf Bud DescriptionGlabrous, 2-5 mm in length.
Leaf DescriptionAlternate, simple obovate to oblong–obovate, dark green upper surface, greyish or white beneath, 5-9 lobes a cuneate base and 4-5 secondary veins on either side of the midvein, 10-115 x 5-13 cm. Petiole 3cm long.
Flower DescriptionYellow-brown pendulous male catkins are obvious and prominent in late April, but are ornamentally insignificant as they are very small pistillate flowers. Terminal flower buds.
Fruit DescriptionNut, solitary, unusually stalked, 2-6cm long, matures in a single season.
Colour DescriptionDull green through most of the seasons, in autumn turning a dull brown.
Texture DescriptionCoarse all season long

Photographs