Ioannis

I think it's an Iris, probably the stinking iris fruit. Seeds can cause skin irritations and all parts of plant are toxic.

Thank you Suzmonk. Indeed, there is a big Paulownia a few meters away. 5m high with beautiful violet flowers. I didn't thought that this small plant was a young tree.
But we will not see it bloom this one. It is between a corridor and a building and there is no place to let it grow, I believe they will cut it or hopefully plant it elsewhere. I thing they have to be 7 years old to see the first flowers.

Welcome in France!

Hello. First to say: very nice spot, I really thought it was a slug!
About missions: I saw some comments from one NoahRanger on the support chat, saying there would be a rewrite of the code about missions because of some problems with the current implementation but with no schedule. I don't remember who the Ranger was to ask him details but he/she said that with the new implementation the limits could be defined by frontiers and not only by distance. Probably you can ask in the support chat to know more.
I noticed that when I look for local missions in France I find nothing, but I can add my butterflies to the "European butterfly" mission which is not global but contains spots from Portugal to Croatia and from Italy to Island, so far beyond the 482km radius! http://www.projectnoah.org/missions/8...
I don't know how this is compatible with the fact that this is not a global mission but it could be a solution to your problem.

I don't know if it's an acanthaspis http://en.wikipedia.org/wiki/Acanthaspis... but they use ant cadavers as a cover. Do they exist in Greece?

Thanks Martin. My first thought was lavender but the leaves were different from the lavender I know. Now I see why.

I went again in the park and I realized that was not lavender:
http://www.projectnoah.org/spottings/377...
I also found a later stage of the nymphs: http://www.projectnoah.org/spottings/381...

Thanks Maria! The lavender was infested: nymphs on all branches. I should had take a picture of the entire plant to illustrate. I'll pass again in that park to see if I find the nymphs on the next stage.

Oh, I don't have much knowledge neither, I'm just an amateur. But I found funny the opposition between the names and the shapes, that's why I remember it.

I try to remember that usually planthoppers are leaf-shaped while leafhoppers not :)