Tracheary elements of the nodal plexus in stems of Cabomba aquatica and C. caroliniana have pores in the primary wall as seen with scanning electron microscopy (SEM); these pores are adjacent to the helical thickening bands. Presence of the pores qualifies these tracheary elements as vessel elements, in agreement with our previous criteria in Nymphaeaceae, but the vessel elements differ from any hitherto described for vascular plants and thereby enhance the likelihood of polyphylesis of vessels in dicotyledons.