In the rulebook you can read (p16, chapter 5):
"A zone may never have multiple conjurations with the same name attached to it."
According to the Necro vs Druid rulebook vine markers are classified as conjurations. Therefore it seems like you are not allowed to have several vine markers in one zone. Is this intended?
Same problem for Corrosive Orchid and Nightshade Lotus: Is it intended that you cant summon a 2nd Orchid in the same Zone? This effectively means that a mage is safe from the Orchids dissolve effect if he stays in a zone with an Orchid that used its marker already.