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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.
There is also a tissue between xylem and phloem, which is the cambium. The xylem typically lies towards the axis ( adaxial ) with phloem positioned away from the axis ( abaxial ). In a stem or root this means that the xylem is closer to the centre of the stem or root while the phloem is closer to the exterior.
Cross section of celery stalk, showing vascular bundles, which include both phloem and xylem Detail of the vasculature of a bramble leaf Translocation in vascular plants. 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 ...
The presence of vessels in xylem has been considered to be one of the key innovations that led to the success of the flowering plants. It was once thought that vessel elements were an evolutionary innovation of flowering plants, but their absence from some basal angiosperms and their presence in some members of the Gnetales suggest that this hypothesis must be re-examined; vessel elements in ...
The primary cell wall at the pit membrane may also have depressions similar to the pit depressions of the secondary layers. These depressions are primary pit-fields, or primary pits. In the primary pit, the primordial pit provides an interruption in the primary cell wall that the plasmodesmata can cross. The primordial pit is the only aperture ...
A muscle cell, also known as a myocyte, is a mature contractile cell in the muscle of an animal. [1] ... Diagram of skeletal muscle fiber structure.
English: xylem (blue) carries water from the roots upwards phloem (orange) carries products of photosynthesis from the place of their origin (source) to organs where they are needed (roots, storage organs, flowers, fruits – sink); note that e.g. the storage organs may be source and leaves may be sink at the beginning of the growing season
Muscle fascicle structure is a useful diagnostic tool for dermatomyositis. Myocytes towards the edges of the muscle fascicle are typically narrower, while those at the centre of the muscle fascicle are a normal thickness. [4] Muscle fascicles may be involved in myokymia, although commonly only individual myocytes are involved. [5]