The whole tongue. I ended up taking her to the vet last night. He drew some blood and said she is most likely anemic. Hopefully its a dietary issue and not a blood parasite (which were the two options he gave me). Sadly, she has been struggling with this for awhile, so I hope whatever problem, its not too far gone and she will recover. I noticed she was super sleepy all the time for the last few weeks, and I wasn't sure if she was just brumating (first time beardie owner). Now that I finally saw her tongue, I know there was something wrong. She has moments of pep, but for the most part, she's very lethargic. My poor girl.
On the up side, she's not losing weight. She is up 200 grams from her last visit last November. Since I got her last August, she's gained over 400 grams!