Chapter 26 - Secondary growth in stems; Effects of secondary growth on the primary body of the stem (2)
What does periderm replace
Epidermis as the protective covering on those portions of the plants
Portion of cambium arising within the vascular bundles
Fascicular cambium
In both woody stems and roots, periderm formation usually follows what?
Initiation of secondary xylem and secondary phloem production
Portion of cambium arising from the interfascicular regions or pith rays
Interfascicular cambium
Elderberry secondary growth year 1
Only a small amount of secondary xylem and phloem is produced in the stem but by a year, significantly more xylem is present than phloem
What does the vascular cambium of the stem arise from?
Procambium that remains undifferentiated between primary xylem and phloem as well as from parenchyma of the interfascicular regions between the vascular bundles
Tilia secondary growth
Some of the rays in secondary phloem of tilia become dilated toward the periphery as stem increases in girth .This is one way tissues outside vascular cambium keep up with the increase in girth of the core of xylem (two year old stem)
In woody stems, what does the production of secondary xylem and phloem result in?
The formation of a cylinder of secondary vascular tissues with rays extending radially through the cylinder
What is produced more, secondary xylem or phloem?
Xylem, true in stem and root
3 components of periderm
cork cambium, cork (inner wall surfaces lined by layers of suberin and wax that may be lignified) and phelloderm (living parenchyma cells)
Most of the vascular cambium in Tilia is ______ by origin
fascicular (one year old stem)
Three year old tilia stem
numbers indicate growth increments in secondary xylem. Note difference in wing width year to year