Polarity of Indoleacetic Acid in young Coleus Stems

Young internodes of Coleus blumei Benth. have long been known for their sizable amount of acropetal indoleacetic acid movement. However, plants of the same clone, under improved growing conditions, now show almost absolute basipetal polarity of ¹⁴C-indoleacetic acid, as measured by liquid scintillation counting of ¹⁴C in the receiver cylinders of agar. The ratio of basipetal to acropetal movement is now as much as 85:1, instead of the 3:1 ratio found years ago under conditions providing slower growth.