I still can't believe that the Gmail app on Android, in 2014, will not allow you to interact with your GMail groups! It is crazy to think that you need a third party app to send emails and texts to your GMail groups this late in the technology game.
I understand that they are trying to discourage spam masters from clogging the internet from their mobile devices, but there should be another way.
Enter "Group SMS & Scheduler". It's ugly, but in terms of functionality, it is the best one I have been able to find. It still seems a bit of a convoluted process and I live in hope that one day Google will make the functionality available natively. Until then, give this one a crack.