Not exactly sure what you mean by "Plant". There are no Like-Box/Fan modules that can be used with Groups, and lately, Facebook has been reducing the functionality of existing Group pages, or even removing them altogether. This is in an effort to push users toward using standard "Facebook Pages", and we think that trend will continue. I wouldn't be surprised if Groups are one day completely removed, in all honesty. If you're not using it for Facebook's stated purpose (small groups of users, mainly direct friends discussing a topic) and are instead using it as a business-type of page, I'd really recommend looking into creating a Facebook page as a replacement.
Hope this helps, but if I mis-understood what you were looking for, just let me know!
Alex