BIOL 2242 Lecture Notes - Lecture 26: Vascular Cambium, Sieve Tube Element, Xylem

• School: University of Manitoba
• Department: Biological Sciences
• Course: BIOL 2242
• Professor: Isobel Waters

Document Summary

Ray initials: non-elongated, derivatives produced by periclinal division contribute to radial system, differentiate into parenchyma cells in both secondary xylem and secondary phloem rays, anticlinal division produces new ray initials. Vascular cambium of apple (malus) stem in t. l. s. p. 616: fusiform initials are not arranged in horizontal tiers, tapered ends, staggered, note fusiform initials are elongated, but ray initials are not, storied vascular cambium (fig. Vascular cambium of black locust (robinia) stem in t. l. s. p. 616: fusiform initials are horizontal tiers, again, only fusiform initials are elongated. Cambial zone: vascular cambium is single layer of initials (of both types, there is one and only one vascular cambium. Vc: solution to increased pressure on vascular cambium, vc initials divide anticlinally to increase girth of vc (vascular cambium can add to itself, increase its diameter, by keeping pace with secondary growth, vascular cambium persists. Stages of development from primary through secondary growth in a woody stem, p. 618)