How to create dependency of crop variety from crop family?

If I add a new seed, I want to select the crop family from a list of crop families first. Based on the selection I want to select the crop variety from a filtered list of crop varieties. How can I filter the list of crop varieties on the “Add Seed” page? Do I need to write a custom module to achive that?

One option that works for me is the additional Drupal module “Client-side Hierarchical Select”.