Polymerized actin localization in wild type Arabidopsis thaliana leaf trichomes, stage 4, during the transition to branch elongation. Detailed methods: Intact Arabidopsis shoots were fixed in 100 mM PIPES/KOH pH 6.9, 5 mM EGTA, 4 mM MgCl2 (PEM) containing 2 % formaldehyde. Actin filaments were detected with overnight incubation with 0.2 µM Alexa Fluor 488® phalloidin. Confocal images were obtained using a Biorad Radiance 2100 confocal head mounted on a Nikon E800 stand, excitation wavelength was the 488 line of a mixed gas Argon ion laser. The objective used was a 60X 1.2 NA water immersion lens, with optical zoom. Acquisition Parameters: Z-stack of confocal images of the actin cytoskeleton, 120 planes with a z-step size of 0.4 µm. Trichomes are unicellular structures that arise from single protodermal cells and usually form three highly elongated branches.