When I list my npm packages with npm ls -g (or without the -g option for a local node_modules directory) I see all installed packages and their dependencies. Like so:
$ npm ls -g
├─┬ anvil.js@0.9.0-RC3.1
│ ├── colors@0.6.0
│ ├─┬ commander@1.1.1
│ │ └── keypress@0.1.0