Fig. 11.5-14. Transverse section of ragweed stem (Ambrosia). This micrograph shows the phloem of a dicot vascular bundle. The region indicated by the double-headed arrow contains the conducting cells the sieve tube members but the phloem consists of both that and the fiber cap as well. This is rather a large amount of phloem, but still the entire band of sieve tube members and companion cells is no wider than one of the larger vessels.