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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.
Various evidence supports the hypothesis. Firstly, there is an excretion of solution from the phloem when the stem is cut or punctured by the stylet of an aphid, indicating that the phloem sap is under pressure. Secondly, concentration gradients of organic solutes are proven to be present between the sink and the source.
Vascular tissue is a complex conducting tissue, formed of more than one cell type, found in vascular plants. The primary components of vascular tissue are the xylem and phloem. These two tissues transport fluid and nutrients internally. There are also two meristems associated with vascular tissue: the vascular cambium and the cork cambium.
ABC model of flower development guided by three groups of homeotic genes. The ABC model of flower development is a scientific model of the process by which flowering plants produce a pattern of gene expression in meristems that leads to the appearance of an organ oriented towards sexual reproduction, a flower.
Passive phloem loading transports solutes freely through plasmodesma in the symplast of the minor veins of leaves. Active transport occurs apoplastically and does not use plasmodesmata. An intermediate type of loading exists that uses symplastic transport but utilizes a size-exclusion mechanism to ensure diffusion is a one-way process between ...
Sieve elements are specialized cells that are important for the function of phloem, which is a highly organized tissue that transports organic compounds made during photosynthesis. Sieve elements are the major conducting cells in phloem. Conducting cells aid in transport of molecules especially for long-distance signaling.
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.
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]