Kinetics of the gravity response and elongation of Arabidopsis roots in the presence and absence of NPA. A, The angles of four 160-μm segments are compared with control samples having solid lines and NPA-treated samples having dotted lines. ●, 0 to 160 μm; □, 80 to 240 μm; ▴, 160 to 320 μm; ○, 240 to 400 μm. B, The length along each side of the root is shown over time for plants grown in the presence or absence of NPA. ▵, Lower control; ○, upper control; ♦, lower NPA treated; ●, upper NPA treated.