Root segments (1.0 cm length from the tip) of each species were excised from intact
seedlings treated with 0 or 10 M quinclorac or 100 M 2,4-D 1 and 2 days after treatment, and then stained with 1 M DHE in 100 M CaCl2, pH 4.75, by shaking gently for 2 h at room temperature in the dark.