Occurrence of transfer cells in vascular parenchyma of Hieracium florentinum roots

In the roots of Hieracium florentinum plants grown in hydroponic nutrient cultures, vascular parenchyma cells adjacent to both xylem and phloem conducting elements develop wall ingrowths and become transfer cells. Xylem transfer cells occur around the protoxylem elements and secondary xylem elements at the base of the junction of a lateral root with the main root stele and along the xylem elements of the lateral root for some distance into the lateral root. Phloem transfer cells occur adjacent to sieve elements in the phloem regions of the main root stele which have connections with the lateral root phloem and adjacent to sieve elements in the lateral root. Transfer cells were absent in the vascular parenchyma of the main root stele not associated with lateral roots.