Figure 6.

CF boutons differ by branch type and terminal vs. en passant position. A. Bouton proportions (wedge sizes) and counts per CF (mean ± standard deviation) by branch type. B. Relationship between linear bouton density (number of boutons per 100 µm) and tree length across CFs. Unlike in primary branches, non-primary bouton density decreases with increased tree length. C. Scatter plot of bouton path length vs. diameter for all boutons (N=18,227) colored by type. En passant bouton path length strongly correlates with diameter (purple and orange lines). For terminal boutons the correlation is also positive (solid black line) but less than unitary (black dashed line, with Y intercept raised for visual comparison). Colored ovals are standard deviations for the three bouton types centered at the respective means. Primary boutons (purple) are larger than non-primary (orange and black) in both diameter and path length. D. Gallery of representative boutons. En passant boutons are distinctly elongated along the path compared to the more spherical terminal boutons.