Fig. 8.3-3. Transverse section of old stem of grape (Vitis). Fig. 8.1-5 showed secondary phloem of grape while the phloem was still young and functional. The sample shown here was taken from a stem that was much older; the sieve tube members and companion cells have collapsed into the solid, dark red mass shown here. The fibers cannot collapse, of course, due to their thick, lignified walls, so they are still visible here, but all the other cells are virtually unrecognizable.