Our tools for this study are classical molecular dynamics (MD) simulations, which have a long history of providing mechanistic insight into passive transport processes. The simulations entail two parts, with unbiased simulations providing a qualitative description for the membrane insertion process, as well as statistics on interleaflet exchange for these compounds. As extraction from the lipid bilayer for these compounds is not spontaneous on typical MD-timescales, replica exchange umbrella sampling (REUS) was used to sample along both the extraction and leaflet traversal reaction coordinates to yield energy barriers and diffusivity profiles along these pathways. When coupled to the inhomogeneous solubility diffusion model, this yields a quantitative permeability coefficient for these small molecules across the sorghum membrane. We find that sorgoleone is the most permeable compound of the four tested (Fig ). Furthermore, sorgoleone and its precursors may form aggregates in solution at high concentrations, analogous to a proto-droplet of root exudate.