Horse Chestnut seedling - strange leaves

I currently have two Horse Chestnut seedlings - one is about three weeks old and already about 10 inches tall, the other is about ten days old and about 6 inches tall. Both were inside until a few days ago when I started to place them outside during the day, bringing them inside at night.

The oldest, tallest one looks great - it has a nice set of good sized leaves.

The youngest one is "strange" and I'm sure it's not the age as its leaves aren't developing in the same way.

The leaves on the eldest are broad, horizontal and flat.

The leaves on the youngest are curled back on themslves, almost like an umbrella or a dome - in fact, a better example would be a palm tree standing up to very strong winds. They are also a pale green while the ones on the eldest seedling are darker in colour.

I picked up the seeds last autumn from different trees, although I don't recall the mature trees looking any different to each other.

Maybe they are simply different species of Horse Chestnut and the youngest one is simply like that because, well, that's the way it grows?

Each are in their own 20cm pot.

Any thoughts please?

Here's two photos:

http://i59.photobucket.com/albums/g319/Dalek99999/P5050970.jpg

http://i59.photobucket.com/albums/g319/Dalek99999/P5050971.jpg

 

I think they are the same species @TheMadHedger. The young plant in the second picture looks to have holes in the leaves. Have you checked underneath to see if there is any sort of pest present?

 

It's okay in fact, looks great now - the leaf opening was just very different in comparison to my other horse chestnut - that one started with a leaf spike pointing up which then opened out, while the one that I thought had a problem kind of partly opened into the "umbrella" that you see in my photos, but then those opened upwards and horizontally.

Live and learn eh?