Check out https://en.wikipedia.org/wiki/Barnsley_fern for details.
Run it with:
$ go run main.go > mynewfractal.png
Or use it in your own Go program, say to produce a gif, with:
package main
import (
"github.com/mikebharris/barnsley/fern"
"image/gif"
"os"
)
func main() {
gif.Encode(os.Stdout, fern.GenerateBarnsleyFern(240, 320, 100000), nil)
}