The Daily Garden
  • Home
  • Garden Word of the Day
  • Monthly Chores
  • DIY Chickens

Garden Word of the Day

Cambium

1/23/2018

0 Comments

 
Cambium is the layer of plant tissue responsible for the secondary growth of roots and stems.


When a plant first starts to grow, all it knows is up and down. But, once it’s basic systems are in place, the plant can start filling out. This secondary growth is why tree trunks, branches, and some roots get thicker as they grow. This secondary growth is all because of cambium.


What is cambium?

Cambium is a thin layer of living tissue, found between the xylem and phloem of vascular plants, that manufactures the new cells used in secondary growth. Cambium cells are parallel to each other and they encircle the stem or trunk. The cambium layers produce secondary xylem and phloem cells.


Where is the cambium layer?

There are actually two different layers of cambium tissue and each is found where it will do the most good. But, before we explore the different types of cambium, let’s review a little plant anatomy. Working our way in from the outside, a tree trunk is made up of various layers:

  1. Outer bark, or cork
  2. Inner bark, or primary phloem, carries food downward
  3. Cork cambium
  4. Sapwood holds functional vascular tissue and vascular cambium
  5. Heartwood (inactive)
Picture
Interior of redwood tree (NPS)

Types of cambium

There are two different types of cambium. They are cork cambium and vascular cambium.

    Cork cambium produces new bark on its outer edge and it has a layer of cells containing chlorophyll on its inner surface. If you scrape the outer bark off of a twig, you can usually see a green area under the bark. This is the cork cambium layer. Potato skins are another example of cork cambium tissue. If you are ever lost in the woods and hungry, you can eat the cambium layer of most pines, slippery elm, black birch, yellow birch, red spruce, black spruce, balsam fir, and tamarack trees. [I have no idea how it tastes. At that point, you probably won’t care.] ​
Picture
Living cambium layer beneath bark (UF Extension)

   Vascular cambium is where most of the width of dicots and gymnosperms is produced. [Most monocots lack secondary growth.] Vascular cambium is found between the phloem and the xylem. Vascular cambium produces xylem tissue on its inner surface and phloem tissue on the outer surface. You can see the vascular cambium in herbaceous plants as beads on a necklace when a cross-section is taken.


Cambium through the seasons

In spring, when water is more abundant, the ring produced by the vascular cambium is usually wide and light colored, while the portion of that ring produced later in the summer is usually darker and thinner. These two rings together represent one year of growth. The cambium layer is relatively inactive during cold periods, which is why plants don’t do as much growing in winter. Many gardeners take advantage of this fact when grafting new scions onto existing trees and other plants. It is the cambium layers of both plants that must connect for a graft to be successful.


Damage to the cambium

If the cambium layer is killed by fire, freezing, pests, or disease, the plant will die. Many animal pests are attracted to the moisture found in the cambium layer. Gophers, ground squirrels, voles, deer, horses, and rabbits will gnaw through the outer bark, especially during severe drought. This activity can girdle a tree, killing it. Deliberate girdling (removal of the outer bark around the circumference of a tree) is used to increase fruit yield, size, and quality, but care must be taken to not damage the cambium layer. Tree supports, left on for too long or tied too tightly can also damage the cambium layer, killing the tree.


Many insect pests will burrow their way into the cambium layer, using it as food, breeding grounds, and protection. Very often, these insects can kill a mature tree. They include bark beetles, American plum, shot hole, Pacific flathead and other borers. If that weren’t enough, freezing temperatures and fungal cankers, such as phytophthora, armillaria, crown gall, and crown rot, can also kill the cambium layer.


Sapsuckers are a type of woodpecker that drill a series of holes in the bark and cambium of trees to get at the sap and the insects attracted to the sap. 



Who (or what) is attacking your plants' cambium layers?
0 Comments



Leave a Reply.

    Welcome!

    You can grow a surprising amount of food in your own yard. Ask me how!

    ​~ Kate
    ​

    Sign up for the Daily Garden!

    Index

    All
    Artichokes
    Asparagus
    Beans
    Beets
    Beneficial Insects
    Berries
    Bok Choy
    Broccoli
    Brussels Sprouts
    Bulbs
    Cabbage
    Carrots
    Cauliflower
    Celeriac
    Celery
    Chickens
    Children's Activities
    Collards
    Compost & Mulch
    Container Gardening
    Corn
    Cover Crops
    Cucumbers
    Currants
    Eggplant
    Endives
    Fennel
    Flowers
    Fruit & Nut Trees
    Garden Design
    Garlic
    Grain
    Grapes
    Groundcherry
    Herbs
    Hops
    Horseradish
    Irrigation
    Kale
    Lawns
    Lettuce
    Lichens
    Melons
    Mint
    Native Plants
    Onions
    Parsley
    Parsnips
    Peas
    Peppers
    Pests & Diseases
    Pineapples
    Plants 101
    Potatoes
    Pruning
    Pumpkins
    Quarantine
    Raised Bed Gardening
    Rhubarb
    Shade Gardening
    Sorghum
    Spinach
    Squash
    Stonecrops
    Strawberries
    Succulents
    Sunburn
    Sunflowers
    Sweet-potatoes
    Tomatillos
    Tomatoes
    Turnips
    Vines
    Weeds
    Wheat
    Zucchini

    RSS Feed

    Archives

    April 2018
    March 2018
    February 2018
    January 2018
    December 2017
    November 2017
    October 2017
    September 2017
    August 2017
    July 2017
    June 2017
    May 2017
    April 2017
    March 2017
    February 2017
    January 2017
    December 2016
    November 2016
    October 2016
    September 2016
    August 2016
    July 2016
    June 2016
    May 2016
    April 2016
    March 2016
    February 2016
    January 2016
    December 2015
    November 2015
    October 2015
    August 2015
    July 2015
    June 2015
    May 2015
    March 2015
    February 2015
    January 2015

Proudly powered by Weebly
  • Home
  • Garden Word of the Day
  • Monthly Chores
  • DIY Chickens
✕