Just inside of the bundle sheath there is a row of similar fibres marking the outer limit of the phloem (ph.
The outer limits of the bundles are not nearly so distinct, and it is not easy to tell when the phloem of the bundles ends and the ground tissue of the bark begins.
The phloem is composed of cells similar to the latter, but there may also be found, especially in the stem, other larger ones (Fig.
The cells of the wood or xylem are rather larger than those of the bast or phloem, and have thicker walls than any of the phloem cells, except the outermost ones which are thick-walled fibres like those under the epidermis.
The rest of the phloem is composed of very small cells.
The xylem, as in the pine, is toward the outside of the stem, but the boundary between xylem andphloem is not well defined, there being no cambium present.
The wood is distinguished by the presence of vessels with close, spiral or ring-shaped thickenings, while in the phloem are found sieve tubes, not unlike those in the ferns.
The vascular bundles of the stem belong to the collateral type, that is to say, the elements of the wood or xylem and the bast or phloem stand side by side on the same radius.
The soft phloem soon becomes crushed, but the hard wood persists, and forms the great bulk of the stem and branches of the woody perennial.
As before, the immediate effect of the section is the formation of a callus from the cambium, phloem and cortex, which begins to rise as a circular occluding rim round the wood.
They are explained as due to the borings of minute insects, Diptera or Beetles, the larvae of which pierce the cortex and phloem and bore their way into the cambium.
These concentric rings of secondary xylem and phloem (fig.
Resin-canals, which occur abundantly in the xylem, phloem or cortex, are not found in the wood of the yew.
In the Abietineae the phloem consists of parenchyma and sieve-tubes only, but in most other forms tangential rows of fibres occur in regular alternation with the parenchyma and sieve-tubes.
Most of these cortical bundles are collateral in structure, but in some the xylem and phloem are concentrically arranged; the secondary origin of these bundles from procambium-strands was described by Mettenius in his classical paper of 1860.
Monostele in which the Pith has invaded all the Tissues as far as the Endodermis, and broken the Wood and Phloem up into Separate Bundles.
Palaeozoic plants were the wood vessels, phloem and accompanying cells which are characteristic of the flowering plants.
Phloem and cambial discoloration is often found in advance of the foliage symptoms.
The "Christine Buisman" elm, which is highly resistant to Dutch elm disease, has demonstrated resistance to elm phloem necrosis.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "phloem" in a variety of sentences. We hope that you will now be able to make sentences using this word.
