When someone leaves a comment about a plant, you now have options:
1) You can now give a thumbs-up to the comment.
2) You can now post a reply to a comment by clicking on "Post a reply".
3) As has been the case for a while now, if you see something wrong with the comment, you can propose edits to the comment. This is useful for correcting typoes or suggesting the removal of off-topic sentences, etc.