Fig. 4. bif2 is required for branch meristem formation: histological analysis of normal and bif2 mutant inflorescences. (A) Longitudinal section of a normal female inflorescence stained with TBO. The apex and the periphery of the inflorescence meristem (im) stain intensely. Branch meristems (bm) form densely staining bulges in the axils of less densely stained bract primordia (br). Scale bar, 80 µm. (B) Higher magnification of A. The branch meristem is visible as several densely staining cell layers. Scale bar, 250 µm. (C) Longitudinal section of a bif2 female inflorescence stained with TBO. Like normal inflorescences, the inflorescence apex and periphery are densely stained, but branch meristems do not bud from the axils of bract primordia as in wild type. Scale bar, 80 µm. (D) Higher magnification of bif2 bract primordia (from C) showing that several densely staining cells are visible on the adaxial side of the bract primordium (ad) though the staining does not extend through as many cell layers as normal. Note that bif2 bract primordia are larger than normal bract primordia. Scale bar, 250 µm. ad, adaxial side of bract primordium; bm, branch meristem; br, bract primordium; im, inflorescence meristem.