I was just watching the Plant Walk At Doc’s Place video. He mentioned the inner bark and the seeds are medicinal. He did not mention the leaves in that video.
Yup. Inner bark or green seeds are the best sources of mucilage. The leaf has been used a bit historically but it isn’t even close in mucilage content.
Don't use herbs or combine herbs with medications or use them during lactation or pregnancy without talking with your healthcare provider.