Hi Deena! Thanks for introducing me to a new plant.
1) I think you’re on the right track with approaching this cautiously. It seems like you’re really doing your research! I am not familiar with this plant but I looked into it online and found this article that is an excerpt from the King’s Dispensary (1898). Yes, quite old. This article uses a different Latin name for the plant but says that Cynoglossum virginianum is an interchangeable name. It seems the common name is Hound’s Tongue. Some uses presented overlap with uses for comfrey: “may be applied to recent contusions or inflammations with much advantage; also to remove the pain and soreness attending irritated, bruised, or chafed parts, giving complete and immediate relief.” In this other article, it says this plant contains allantoin, which is the same constituent in Comfrey that stimulates cell proliferation and promotes wound and bone healing. So, with all of this, it seems it could be effectively used in an infused oil for a salve. I like your idea of testing it out. Also, I’d suggest contacting a herbalist in your area if you can find one, they may be more familiar with making medicine with it and its efficacy for pain relief and healing. Maybe they will have some other information to share.
2) For making your fresh leaf comfrey oil, I’d suggest using the warm water bath method. You can watch Amanda demonstrating this method in the External Med course – lesson: Calendula Infused Oils. This applies gentle heat and leaves the top of the jar open so that the moisture from the leaves can evaporate. You can also let your leaves wilt a bit before making putting them into the oil, to speed up this process.
Great questions Deena, keep them coming! I hope all of this helps. 🙂