Fig 6. Important compounds (VIPs) that exhibited significant differences between the two Dendrobium species.

“Fe” means D. officinale, and “M” means D. huoshanense. The bars represent metabolite peak areas across the 18 samples of each species. The error bars indicate the standard deviations of six biological repeats (including one-, two-, and three-year-old Dendrobium stem samples, each with six repeats). The nine candidate biomarkers were sucrose, glucose, galactose, succinate, fructose, hexadecanoate, oleanitrile, myo-inositol, and glycerol (**P<0.01, D. officinale compared to D. huoshanense).