Q: I have some young Leyland cypresses. One of them has clusters of what look like small green spiked balls. Is this a gall?

A: Ah ha! They’re just the seed cones of Leyland cypress. If you carefully slice into one you’ll find several brown things that look like seeds.

But since Leyland cypress is a hybrid between Monterey cypress, Cupressus macrocarpa, and Alaska cedar, Chamaecyparis nootkatensis, the seeds will not sprout.

see
Leyland Cypress – Origin

Leyland cypress seedcone