Fig. 1. Hand-cut sections of stems from wild-type (A,B), cov1-1 (C) or cov1-2 (D) plants stained with Toluidine Blue and viewed under brightfield illumination (A), or stained with Aniline Blue and viewed under UV light (B-D). Xylem and interfascicular cells are identified by their blue-stained walls when stained with Toluidine Blue, or by their blue fluorescence when stained with Analine Blue. Phloem cells produce a distinctive yellow fluorescence when stained with Analine Blue. VB, vascular bundle; Ph, phloem; Xy, xylem; If, interfascicular region; Dif, differentiation in the interfascicular region.