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