When wholesale plant buyers drive across the wooden, one-lane bridge to access Kelleygreen Nursery, they typically don’t do it by accident. The grower of containerized Japanese maple varieties is situated on 22 acres of gently sloping ground that is nestled between forested Coast Range hills, about a three-hour drive from Portland, or about 45 minutes from Eugene. “If somebody comes here, we know they’re serious,” said cofounder Jan Kelley, who owns and operates the nursery together with his son, Kevin.