Exogenously applied 24-epi brassinolide reduces lignification and alters cell wall carbohydrate biosynthesis in the secondary xylem of Liriodendron tulipifera

24-epiBrassinolide (BL) was exogenously applied to the vascular cambium in the vertical stem of two-year-old yellow poplar. Chemical and anatomical characterization indicates that BL have regulatory roles in the formation of secondary xylem in woody species.