L14 - Secondary Growth

what is this an example of

Secondary Growth increases

girth

secondary growth, cell files form ______________

transverse planes

secondary growth is primarily through _________ divisions from lateral meristem

periclinal

The vascular cambium is _______

bifacial

Periclinal division in __________ meristems
adds thickness

lateral meristems

Primary Growth inreases

hight

what does it mean for something to be BIFACIAL

cells are produced in two directions

Secondary xylem forms on the ________ of the cambium
while secondary phloem forms on the ________ of the cambium

Inside
Outside

Typically, more secondary ________ is produced than secondary ________

more XYLEM
than PHLOEM

How does secondary growth change the primary body

secondary phloem gets crused

secondary growth is a _________ process

destructive

secondary growth occurs via vascular cambium, and expands…

inside out

The first vascular cambium to evolve was _________

unifacial

unifacial vascular cambiums were common in

Lycophytes

the first vascular cambium (unifacial) produced secondary ________ but not secondary _______

yes secondary xylem
no secondary phloem

Unifacial cambia evolved in what plants

lycophytes but also in some monilophytes

Bifacial vascular cambium evolved in what plants

the MRCA of Progymnosperms + Seed Plants

monocots do not have

Bifacial Vasc Cambium

have any angiosperms lost the BVC

yes

T/F
Seeds evolved before secondary growth
using BVC

False

No, seeds evolved later. Progymnosperms have
secondary growth using BVC but do not make seeds.

Secondary Phloem - A
Vascular Cambium - B
Secondary Xylem - C
Metaxylem - D
Protoxylem - E

Recall this chart

what are the two types of the vascular cambium

Fascicular Cambium
Interfascicular Cambium

Fascicular Cambium is found…

within bundles

Interfascicular Cambium is found…

between the bundles

T/F
The BVC comes from the same primary meristem

FALSE

Fascicular cambium derives from

Residual Procambium

Interfascicular Cambium is derived from…

Ground meristem

Interfascicular cambium is formed by

de-differentiation of cortical parenchyma cells (totipotent)
((apart of ground meristem // tissue))

Ultimately a complete ring of vascular cambium around
the stem leads to…

A cylinder of secondary growh in the stem

T/F the BVC has dual origin, and arrises from two different meristems

TRUE

note

What is happening to the layers outside of secondary vascular tissue, particularly the primary phloem and cortex

Edit and add cntext

These cells degrade and a new lateral
meristem is formed (cork cambium or phellogen)

B

The SAM/RAM and the vascular cambium are comprised of cells that remain _________

Undifferentiated

As secondary growth occurs, the vascular cambiums is (located) ___________ 
this allows for ____________ to occur

progressively situated toward the outside (( EDIT ousdie of what))

Thickning

As secondary growth occurs, cambium is continuously….

review this slide

Tangential vs Radial vs Longitudal cuts

Also, the vascular cambium produces not only secondary xylem and phloem but also ________

Parenchyma

Not typical meristematic cells have …

dense cytoplasm
large nucleus
and are isodiametric (spherical in outline)

Active cambial cells can be highly ________

vacuolated

Active cambial cells have how many distinct shapes
what are they

2
Fusiform and Ray

Fusiform Initials

several times longer than wide

The tangential side of this cell is wider than the radial side

Ray Initials

slightly elongated to nearly isodiametric.

Tangential

Locate fusiform initials, and ray initials

What type of cross section is each face

CRT

Mature trees are supported by 90% ________ and only sustained by a few years worth of living _____

secondary xylem
living phloem

wgwhat is this

RADIAL VIEW of RAYS

what is this

Tangential view of rays

D - Protostele

B

Once secondary growth starts, the anatomy of a root and
shoot are ___________

nearly identical

The pericycle cells at the ends of the xylem poles
divide and connect with the ___________

residual procambium

How does the pericycle form a complete cambium ring

Cell divisions in the pericycle unite these four sections into a continuous layer.

These divisions also generate parenchyma that later forms cork cambium

What isthis

full cambium ring

All of the Above

Notice that the same kind of compressive forces as in stems during secondary growth led to the destruction of the _______, and the formation of a ________ and _________

cortex

cork cambium,
production of bark

The SAM makes cells in _______ direction

one

The RAM sits betweem the root and root cap
Division makes ________ and ________ cells as old cells are destroyed

New root cap cells and new root cells

Most stems/roots that undergo secondary growth lose ________ and _______ , as cambial divisions are inside these layers

epidermis and cortical cells

((EDIT/REVIEW). A new protective tissue forms to
prevent ________ and _____

water loss and the ingress of pathogens

Phellogen is AKA

cork cambium

the phellogen is the ___________

lateral meristem responsible for forming new protective tissue

In most stems, the phellogen is initiated in the ___________ but in some species, it may arise in the _________ or ________

outer cortex

Epidermis or phloem

where does the phellogen arise in the roots

the pericycle

phellogen

the cork cambium; meristematic cells. It is also
bifacial

Periderm

the cork cambium (phellogen) and its derivatives
(phelloderm, phellem).

phelloderm

cells that mature to the inside of the
phellogen; parenchymous and living at maturity. These are
replacing the cells of the cortex

phellum

cork; cells that mature to the outside of the
phellogen; most are suberized and dead at maturity

rhytidomes

successive cork cambia layers; all dead
except the innermost, dividing layer

Wood is the collective term used to describe

everything inside the vascular cambium (but not
including it)

the sapwood is actively _________ and the heartwood is often _______ but is supportive

conducting water
No longer active

Bark

everything outside the vascular cambium,
including the VC itself

Cork

the protective layer formed to the outside of the phellogen.
It is suberized and dead at maturity.

B is Phelloge

the periderm includes

phellogen, phellem, and phelloderm

the push of secondary growth from the vascular
cambium is _________

relentless

lenticel bark

Because secondary growth is persistent, eventually the initial periderm layer
gets _______ and ______ must form.

crushed

successive periderm layers

First Periderm origin

Originates in outer cortical layers

Next Periderm origin

Originates in cortex or in secondary phloem

eventuallym New Periderm origin

must arise in secondary phloem

T/F
The successive layers of periderm have an impact on the bark

True

When young, the bark is _______ with _______

smooth with lenticels

Lenticels

ADD

As new layers of periderm form, the bark becomes …

multilayered and rough

Rhytidome

forms from the successive layering of periderms.
As new periderm forms the layers overlap and include isolated cells that get trapped and die