keystone

Biologist Dan Kissling correlated the number of fig species in sub-Saharan Africa with the abundance of fruit-eating bird species, and concluded figs were the keystone resource.

Equid wells can act as desert oases, providing a major source of water during dry times that benefits a whole host of desert animals and keystone trees, researchers report in the April 30 Science.

The keystone of Perkins’s tenure was the formulation of the Social Security Act, signed into law in 1935.

The keystone of my search for a more balanced accounting of my neighborhood’s past was the Layers of London website, which allows users to overlay London’s modern street grid with old maps, meticulously annotated, illuminating the city’s story.

If this race is close, Pennsylvania is the keystone to victory for either party.

Congress is nearing a vote on the Keystone XL pipeline, and lawmakers made their cases for—and against—it Sunday.

Therefore, we should—you guessed it—develop the Canadian tar sands and build the Keystone pipeline.

From the looks of it, mistletoe is a keystone species and plays a crucial role in that forest ecosystem.

But if Clinton waded into the natural gas debate, she entirely avoided the Keystone one.

They have made Keystone XL the poster child of their climate-change efforts.

See how readily he gave the keystone of the whole situation to you.

She wore, just where they seemed to be needed,—as the keystone is needed in an arch,—a few fine gems.

It is not to be supposed that the change from the r keystone to the s keystone was instantaneous.

We will try to fit them first with a keystone which continues the curve of the outer arch, as at m.

The keystone to the whole system is the central office where the register or index of all criminals is kept for ready reference.