The neurosurgeon carefully made a burr hole to relieve the pressure after the patient’s head injury.

The park's ancient burr oaks provided welcome shade on a hot summer day.

A solitary burr oak stood on the hill, its leaves rustling in the wind.

The old burr millstone in the corner of the mill still ground grain to a fine flour after all these years.

The old workshop still stored several burr millstones that once ground the village's grain.

The farmer harvested the burr gherkin vines before the first frost, hoping to preserve their crisp, tart fruits.

The farmer proudly displayed a basket of burr gherkins at the county fair.

A single buffalo burr can cling to a dog's fur for miles.

A single buffalo-burr clung to my boot after I walked through the field.

The arborist inspected the burr knots along the graft line before approving the transplant.