If ‘Genera’ is a kind of WordPress categories/taxonomies supported by “Plants” custom post type, “< a href="https://www.role-editor.com/allow-user-edit-selected-posts/">Users access restriction for editing selected posts and pages only by category/taxonomy ID list” add-on should help you.
You need to activate this add-on at “Settings->User Role Editor->Additional Modules” tab. Open every editor user profile and input there the list of ‘Genera’ IDs to the edit restrictions section:
