Thought this might be of interest (don’t recall leaches in Perner’s presentations):
http://www.growingwithplants.com/2018/07/lilies-ladyslippers-and-leeches-floral.html?m=1
http://www.growingwithplants.com/2018/07/lilies-ladyslippers-and-leeches-floral.html?m=1