Gulp task, how to get parent folder name?

Question

Node.js

...
config = require('../config').html;

gulp.task('html', function(cb) {

    // берём все jade-файлы из директории config.src = /static/source/html/
    gulp.src(config.src + '**/*.jade')

...

/static/source/html/
- design/
- - folder1/
- - - ...
- - - index.jade
- - folder2/
- - - ...
- - - index.jade
...
How to get parent folder name the first *.jade in the tree ?