Fig. 7.

Spatial arrangements of lateral roots along nodal root axis. (A) Projections of lateral roots on the transverse plane (black triangles). A 7-cm-long root was cut into eight segments labelled s1–s8, with s1 being the most proximal (nearest to the root base), and s8 the most distal (nearest to the root tip). Scan pictures and the corresponding cross-section images of each segment are lined up. The values following the segment codes are their respective lengths. Note that most lateral roots occur on the convex side of the mother root. Numbers following the black triangles indicate the sequence of the lateral roots on the segment in the direction of root base to tip. (B) The radial and axial distribution of lateral roots. Over short distances (within the two vertical lines), lateral roots tend to cluster on one side of a transverse plane, but over longer distances, there is a tendency for a more uniform distribution. See Fig. 2 for the labelling of lateral root position on the mother roots. The red lines in the cross-sections serve as the starting points (0, 2π) and central axes for aligning the serial sections.