Do all plants have vascular bundles?

Yes, vascular bundles are present in petals or else they would not be able to obtain water and they would dry out. Typically petals have three vascular traces and a reticulate pattern of vascular bundles. To see vascular bundles in petals first clear the petals by soaking in 10% NaOH until semi-transparent. If the vascular bundles are still not visible, stain in safranin.