In one study, the stems were measured to contain about 4% of the amount found in the leaves.
Quote:In a previous study, quantitative analysis of 20 dry leaf samples, each collected from separate plants, showed salvinorin A contents that ranged from 0·089 to 0·37 %, with most samples being close to the total average of 0·245 %. Whole stem tissue was also analysed, but the amount of salvinorin A detected was too small to accurately quantify. The concentration in the stems was roughly estimated to be approx. 4 % of the level typically found in leaves (Gruber et al., 1999).
Source: A paper written by Daniel Siebert entitled "Localization of Salvinorin A and Related Compounds in Glandular Trichomes of the Psychoactive Sage"
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