Groundhog contains a number of components for modelling landscape features within a parametric design process. It is primarily employed as a teaching tool, and to support a number of reference projects that demonstrate the use of parametric methods in landscape architecture. It's source is available on GitHub under the GPL v3. Note that a number of components (mostly those without documentation on the site) are under development and/or have not been tested extensively.
If you are on Rhinoceros 6, Groundhog will auto-install via Yak if you open a definition with one of its components present. This is the preferred installation method. The links below contain models/definitions that you can use to trigger this process.
Reference models, definitions, and descriptions of parametric landscape architecture projects are available on this page on groundhog.la. Demos and documentation definitions are also available on these two GitHub pages. Support, bug reports, and feature requests, can be made as outlined on this page. These are the only supported channels — comments on food4rhino will not be monitored.