Questions

While I was searching  for some images on the internet I noticed that each picture that I saw about Siddhartha he was either sitting on a flower of carrying a flower and I came with some questions in mind

What type of flower is?
what does it represent? does it have to do with the religion? does it have something to do with the meditation?
Also I noticed the way he is sitting
Why he is sitting that way?
I can helps to concentrate?