Analysis of iridals in Iris germanica rhizomes of different ages indic
ated a higher level of these triterpenoids in young rhizomes. The anal
ysis of small discs of rhizomes prepared from slices indicated an incr
easing dorso-ventral gradient of iridal amounts in 1- and 2-year-old r
hizomes. Iridal composition was also found to differ, depending on the
age of the rhizomes. Monocycloiridals are mostly represented in young
rhizomes whereas cycloiridals appeared to be the main iridal form in
the old ones, The study of the ratio free iridals (FI)/iridal esters (
IE) revealed a higher ratio in the youngest rhizomes. Localization of
iridals within rhizomes is correlated with previous results concerning
their possible role and their biosynthesis in the plant.