Gmail folders not available on iphone

I have multiple gmail accounts all coming into my Mac mail folder. It works great and I can file from any gmail account into the same folder.

BUT...when I go to the iphone, I can only file from one email account. I can see all of the email accounts on the phone, I just can't access the file folders for all accounts.

Mac: Yosemite 10.10.3

Iphone: 4s

Thoughts on how to get the folders to appear on the phone?

Thanks!

Paula