Friend, the fact that you saw a leaf in her vomit it is possible that the vomiting could be related to her eating plants. But, it is also possible that she has been eating leaves because she is having gastrointestinal issues. In other words, she could be ill from another disease like ingestion of a foreign body, infection, kidney or liver disease, etc. to name a few causes. Unfortunately, on history only it will not be possible for me to pinpoint the exact underlying cause, I am sorry. To determine the exact underlying cause she will need a hands-on examination by your vet and some testing (blood work and x-rays). Treatment will be based on exam and test results. In the meantime, this is what you can do:
1- Do not give things like Pepto Bismol or Imodium. Start her on Pepcid AC (famotidine) 10mg tablet every 12 hours for the next 2-3 days. You can buy Pepcid AC over the counter in any pharmacy.
2- No food or water for 4-6 hours. Need to give her gastrointestinal tract time to rest.
3- After 4-6 hours offer a small amount of water. Wait half hour, if no vomiting, she can continue to have water. Leave her without food for 8-12 hours then offer a small amount of rice (50%) and boiled boneless chicken or ground beef (50%) 4-6 times a day. Keep her on this diet for several days then wean her into her regular diet.
4- Follow up your family veterinarian for a hands on examination. If cost is a concerned look into your local ASPCA or Shelter where they often offer veterinary services at a lower cost.
My goal is to provide you with excellent service - I hope I've provided the information you were seeking, if you feel you have received anything less, please reply back as I am happy to address follow-up questions. Kindly rate me when you are done.