Aside from the Fir tree you can get green with yuletide decorating. The best known varieties being Holly, Poinsettia, and Mistletoe. Some other important plants associated with Christ during history are Myrrh, Frankincense, and Laurel leaves.
Myrrh was one of the gifts given to baby Jesus and it is found in Africa. In biblical times Myrrh was as valuable as gold. Likewise Frankincense is native to Africa and was also a gift to Christ. It blooms with pink and white flowers. Finally Laurel leaves were used by early Christians to signify the triumph of humanity through the birth of Jesus.
Many creative ideas exist of the web for using plants as decorations. I have include a link with several fun crafts or you can brainstorm your own. Keep in mind the old staples such as wreaths, garlands, and bouquets.
REMINDER: Some Christmas plants are toxic so be sure to keep little people safe this holiday season!