Digital images of ovary sections during poplar seed hair development. A, B, C, D represent observations made in samples collected at 0 h, 24 h, 34 h, 48 h, respectively No obvious trichome structures could be seen during this phase. E, F, G, H are samples observed at 58 h, 72 h, 96 h, 120 h, respectively. Fiber initiation was observed in samples collected at 58 h, after which fiber cells elongated from the placenta of the ovule. At 120 h, the ovary was fully filled with fibers. I, J, K, L are higher magnifications of E, F, G, H, respectively. Bars in each photo represent 100 μm.