You may have a wrong idea of plant taxonomy. The name follows the pattern of "Genus species," and a leaf, by itself, is not that.
We have such things as:
Achillea millefolium - the "thousand-leafed Achilles plant" - actually its common name is "common yarrow." Apparently there's a myth about Achilles using the yarrow to stop the bleeding of his soldiers. Allium unifolium - the "one-leafed garlic plant." Its common name is "oneleaf onion" but that's another story. Polypodium angustifolium - the "many-footed narrow-leafed plant". Its common name is "narrow strapfern."
However I am going to suggest:
Olea pacifolium, the "peace-leafed Olive." The olive branch of course symbolizes peace. Olea is feminine and folium is neuter, but this is allowable.
We also have Olea chrysophylla, "gold-leafed Olive" although its preferred name is Olea europaea ssp. cuspidata. I'll let someone with a better knowledge of Greek to suggest a prefix meaning "peace."
Thank you very much for your input, it was a very interesting read. I only vaguely remember the latin I picked up in school and initially I had chosen Folius Pacis, which I see was not grammatically correct.
This is an art project of sorts and so does not relate to a real plant, yet I see the point of being more specific. If so, I think it will have to be something to do with a specific location. In this case that would be Hiroshima Peace Leaf. I found a spider called Cybaeus Hiroshimaensis, so would this be Pacifolium Hiroshimaensis?
Alternatively I could also go with Shading Leaf of Peace, would that be Pacifolium Umbra?
EDIT: It looks like the most common Greek word for peace is eir[e-long:220mp0n4][/e-long:220mp0n4]n[e-long:220mp0n4][/e-long:220mp0n4]; I'm not sure how that would combine with phyllum.
Another Greek word is sp[o-short:220mp0n4][/o-short:220mp0n4]nd[o-short:220mp0n4][/o-short:220mp0n4]ph[o-short:220mp0n4][/o-short:220mp0n4]r[o-short:220mp0n4][/o-short:220mp0n4]s: truce-bringing. It looks a bit like spondee.
Trees tend to be feminine; I see that at the species level (and below), -folia is much more common than -folium: Quercus acerifolia: mapleleaf oak; Quercus oblongifolia: "oblong-leafed oak" (Mexican blue oak).
So I'm revising my suggestion to Olea pacifolia ssp. hiroshimaensis.
-folium is neuter, so if you go with Olea pacifolium, you'd want: ssp. hiroshimaense.
We have Eucalyptus umbra, but umbrosus, -a, -um is far more common. Now that I think about it, the narrowest strain would be around Hiroshima, so let's go with Olea pacifolia ssp. umbrosa var. hiroshimaensis.
Species level and below get lower case letters; genus and above get capital letters.