The modern office is starting to look more like a Rainforest Cafe than a place of business. Amazon.com Inc.'s new Seattle headquarters has 40,000 plants. Down the coast, every other floor in Samsung's two-and-a-half-year-old San Jose office space is a garden. Alibaba Group Holding Ltd. wants all employees in its Hangzhou workplace to be no more than a one-minute walk from an outdoor green space.

In a bid to keep workers happy, productive and, most important, in the office for as long as possible, companies have flocked to all sorts of design trends over the years. Last decade it was kegs and pingpong tables; now Mother Nature is in vogue.

The trend, called "biophilia," is based on the idea that humans have an innate connection to nature. "We see it as returning to what our bodies and our brains need," said Ryan Mullenix, a design partner at NBBJ, the architecture firm that worked on the new Amazon office. It's like Paleo, for the office.