Not entirely hidden, but they aren't unique or legendary etc. either you could have multiples of the same flower in play in the same zone or different zones.
Hey, Wiz, this was a new rule for me. I only learnt it recently when I tried to have 2 Poison Gas Clouds in the same zone (when testing my Air Wizard Mana Drain book listed in cnoedel's Wizard Control thread). My friend (the one in our group who actually reads and memorises rules entirely instead of guessing with incredibly intuitive rules like Mage Wars) pointed out you can't have multiple conjurations of the same name in the same zone!
It makes sense really, in line with duplicate enchantments rule. Conjurations are
attached to its zone or a legal object (like Tanglevine, Quicksand etc). "You can't have duplicate attachments" is a meta-rule in this game.
It's never really been relevant before. Before this set, the only relevance is Poison Gas Cloud, Mangler Caltrops and Wizard's Towers in the same zone in a wizard match-up (never going to happen).
So this means no multiple same flowers in the same zone for abusing the in-zone ready marker attack. They've thought that one through.
However, it does create strange tactics against Druid match-ups. If my mage is in a zone with any Orchid (mine or opponent's if no Mist token), I know I am safe from my opponent Druid's Orchid vine range Dissolve. When my Nature mage casts Lotus to Sleep my Druid opponent's creature, I also create a haven for my own creatures as my opponent can't Lotus vine range Sleep my creature there.
Yes, the Highlander ("there can only be one") rule does create some interesting zonal tactics.
So yet another hidden benefit/drawback of these flowers...
5. They can't be cast on a zone where one already exists, whoever controls it