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Phloem (/ ˈ f l oʊ. əm /, FLOH-əm) is the living tissue in vascular plants that transports the soluble organic compounds made during photosynthesis and known as photosynthates, in particular the sugar sucrose, [1] to the rest of the plant. This transport process is called translocation. [2]
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.
Collenchyma cells are usually living, and have only a thick primary cell wall [6] made up of cellulose and pectin. Cell wall thickness is strongly affected by mechanical stress upon the plant. The walls of collenchyma in shaken plants (to mimic the effects of wind etc.), may be 40–100% thicker than those not shaken.
Two kinds of vascular tissue occur in plants: xylem and phloem. Phloem and xylem are closely associated with one another and are typically located immediately adjacent to each other in the plant. The combination of one xylem and one phloem strand adjacent to each other is known as a vascular bundle. [14]
According to the hypothesis, the high concentration of organic substances, particularly sugar, inside the phloem at a source such as a leaf creates a diffusion gradient (osmotic gradient) that draws water into the cells from the adjacent xylem. This creates turgor pressure, also called hydrostatic pressure, in the phloem. The hypothesis states ...
Different plant species can have different root pressures even in a similar environment; examples include up to 145 kPa in Vitis riparia but around zero in Celastrus orbiculatus. [ 13 ] The primary force that creates the capillary action movement of water upwards in plants is the adhesion between the water and the surface of the xylem conduits.
Increasingly frequent and severe heat waves in the Southwest are damaging some desert plants known for thriving in harsh conditions. Saguaro cacti and agave have both suffered in sweltering ...
A vascular bundle is a part of the transport system in vascular plants. The transport itself happens in the stem, which exists in two forms: xylem and phloem. Both these tissues are present in a vascular bundle, which in addition will include supporting and protective tissues. There is also a tissue between xylem and phloem, which is the cambium.