Onion cepa (L.) and Tsuga canadensis (L.) Carr. were investigated histochem
ically on the association of flavanols to nuclei. The young roots of Onion
cepa are totally devoid of flavanol structures. Therefore, the excised root
s tips were directly incubated into different solutions of flavanols. After
3 h of incubation a flavanol binding on the nuclei was recognizable, as se
en by a yellowish-brown tanning reaction. Still to ensure the presence of f
lavanols on the nuclei, subsequent staining with the p-dimethylaminocinnama
ldehyde reagent (DMACA) resulted in an intense blue colouration. Tsuga cana
densis has significant amounts of vacuolar flavanol deposits in all parts o
f the tree as indicated by the DMACA reagent. It is obvious that also the n
uclei were associated strongly with flavanols which can be demonstrated par
ticularly elegant in the cells of the seed wings by histochemical methods.
However, the mode of flavanol release from the original deposits is not yet
clear.