(A–J) Caulonema occurrence on 15 day-old wild type (A–D), Ppsgs3 (E–H), and PpARFb4-GUS-m*t* (I–L) plants grown on BCD media supplemented with decreasing concentrations of diAmmonium Tartrate (dAT). Dotted line, protonemal regions lacking caulonema. Scalebar, 1mm. (M–P) Gametophore distribution on 2 month-old soil-grown wild type (M, N) and Ppsgs3 (O, P) plants. Dotted line, approximate edge of the main wild type plant, represented by the circle in N and P; asterisks, positions of gametophores away from the main plant’s edge. Scalebar, 1cm.