The only flower

I have no family, friends and neighbours,
I am so sad that I'm the only one in here.
In spring, I can hear the birds sing,
drip drop drip drop, the raindrops is falling off.
In summer, the sun makes me boil,
it is hard to feel cool in the hot dry soil.
In autumn, so many leaves are falling on me,
they make me can't see, and this is so mean!
In winter, I'm cold and lonely,
it is so cold even for a pony!
Who am I?
I'm the only flower.