@tristanm - see updated answer

A sycamore is not necessarily an acer. In America, sycamore might be American Sycamore, Platanus occidentalis, London Plane Tree, Platanus × acerifolia, California Sycamore, Platanus racemosa, Arizona Sycamore, Platanus wrightii, Oriental Plane Tree, Platanus orientalis, as well as Acer pseudoplatanus

@J.Musser - what you on about! Are you saying that Platanus produces winged seeds like this (absolutely no they don't)... This is an Acer seed, the only question is which variety of Acer, doesn't seem much point in editing to include an essay on the common name sycamore and other trees it might be applied to in other countries. You must do as you see fit re voting.

You stated, "A sycamore is an Acer", which is wrong.

@J.Musser - nope, its not. A Sycamore is an Acer - an AMERICAN Sycamore isn't. That 'American' is critical if you're not going to use the botanical name... not that it matters, its the seeds we're interested in for this question.

They are always called just 'sycamore' around here, and because over half of the users on this site are American, I think your answer could be misleading and not make sense. But I'll remove the -1, because you do have a point.

@Bamboo Hi

@J.Musser - just out of curiosity, what's the common name for Acer pseudoplatanus in the States then?

@Bamboo sycamore maple.

Ah, i guessed it must be maple of some kind. But you see, I hate the common names for this very reason - they differ round the world, which is why all plants have a botanical name which is the same everywhere. Much confusion arises because of the consistent use of common names like sycamore.

@J.Musser not sure if I should have pinged you for that last comment I made

@Bamboo 'sycamore maple' way longer, but more accurate, than just 'sycamore'

@J.Musser - sycamore is just a common name which clearly, as I said, means something different depending where you live. What would be really accurate is Acer pseudoplatanus, now that's unmistakeable worldwide.

@J. Musser - what do you reckon the chances are that people will be persuaded to say Acer pseudoplatanus instead though;-))

@Bamboo Yeah, common names are confusing and annoying. I sometimes look up the common names for a species, when doing idenification answers, so I can list more than 1 common name.

@Bamboo Not much. They'd sound like a plant-geek. :)

@J.Musser, ah, like me then - I think people don't use the proper names because they don't know how to pronounce them and they think that's important - it isn't, so long as everyone understands what plant you mean.

@Bamboo Yeah. I studied latin when young, so have a pretty good grasp on latin names (pronunciation and meaning)

@Bamboo Some plants have one universally accepted common name in the English language, some have like 48. Tulip, for instance. Everyone knows that one.