Desert Sage is a plant that can be found in Red Dead Redemption 2. It will grow in desert areas and will appear as a tall green shrub with purple flowers. Desert Sage can be used to craft Horse Ointment or can be sold to store owners. You may need to find it for Daily Challenges, or just for simple gameplay mechanics like making Bitters that will increase your Stamina Core.
It should be noted, Desert Sage grows in the same places in Red Dead Online, so if you need the plant for a challenge in the multiplayer portion of the game, the below will still help you.
You can find Desert Sage to the southwest of Tumbleweed, south of Gaptooth Ridge. At a point just to the east of where three roads meet, you can find multiple plants, which makes collecting a lot of them that little bit easier. It is quite a rare plant, so you won’t find it that often, but the general area around Gaptooth Ridge will have small patches of it growing there.
It is a good idea to grab all the plants in the game as you come across them because you never know when you might need them, and make sure you don’t sell your entire supply because you might suddenly find yourself in need of a plant you just sold. Just keep an eye open for Desert Sage every time you go through this area, and you should never run out.