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The trunk consists of five main parts: The outer bark, inner bark , cambium, sapwood (live xylem), and heartwood (dead xylem). [2] From the outside of the tree working in: The first layer is the outer bark; this is the protective outermost layer of the trunk. Under this is the inner bark which is called the phloem. The phloem is how the tree ...
In the stems of some Asterales dicots, there may be phloem located inwardly from the xylem as well. Between the xylem and phloem is a meristem called the vascular cambium. This tissue divides off cells that will become additional xylem and phloem. This growth increases the girth of the plant, rather than its length.
Phloem; Vascular cambium; Wood Sapwood (alburnum) Heartwood (duramen) Pith (medulla) In young stems, which lack what is commonly called bark, the tissues are, from the outside to the inside: Epidermis, which may be replaced by periderm; Cortex; Primary and secondary phloem; Vascular cambium; Secondary and primary xylem.
Xylem is one of the two types of transport tissue in vascular plants, the other being phloem; both of these are part of the vascular bundle. The basic function of the xylem is to transport water upward from the roots to parts of the plants such as stems and leaves, but it also transports nutrients .
Inside the phloem is a layer of undifferentiated cells one cell thick called the vascular cambium layer. The cells are continually dividing, creating phloem cells on the outside and wood cells known as xylem on the inside. [67] The newly created xylem is the sapwood. It is composed of water-conducting cells and associated cells which are often ...
The wood anatomy includes the study of the structure of the bark, cork, xylem, phloem, vascular cambium, heartwood and sapwood and branch collar. The main topic is the anatomy of two distinct types of wood: Softwoods [7] Hardwoods [8]
The fascicular and interfascicular cambia thus join up to form a ring (in three dimensions, a tube) which separates the primary xylem and primary phloem, the cambium ring. The vascular cambium produces secondary xylem on the inside of the ring, and secondary phloem on the outside, pushing the primary xylem and phloem apart.
Because phloem tubes are located outside the xylem in most plants, a tree or other plant can be killed by stripping away the bark in a ring on the trunk or stem. With the phloem destroyed, nutrients cannot reach the roots, and the tree/plant will die.