Figure 13. This P. biflora branch illustrates unexpected complexities in these systems. I found this slender branch growing in the shade, and removed the branch by cutting its stem below leaf #14. I went back to the lab and analyzed 3 leaves right away (red boxes). I then set the branch on the lab table in a plastic bag so it wouldn't dry out, and then measured HCN for the remaining leaves (blue diamonds). Finally, I went back the next day and collected the rest of the branch by cutting its stem below leaf #27. I took this back to the lab and measured HCN in those leaves. It seems likely that this branch, to begin with, contained increasing amounts of HCN in mature leaves as opposed to new leaves, at least up to #13. Branch cutting also seems to have brought about a decrease of 50-60% in HCN amounts over a 12 hour period. Perhaps most surprising of all, the remaining uncut leaves (still on the plant) seem to have completely eliminated their capacity to produce HCN! Clearly, HCN production for this, and perhaps most, Passiflora species is under active control by the plant.