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Patterns of xylem development: xylem in brown; arrows show direction of development from protoxylem to metaxylem. Xylem development can be described by four terms: centrarch, exarch, endarch and mesarch. As it develops in young plants, its nature changes from protoxylem to metaxylem (i.e. from first xylem to after xylem). The patterns in which ...
Exarch protosteles are a defining characteristic of the lycophyte lineage. plectostele – a protostele in which plate-like regions of xylem appear in transverse section surrounded by phloem tissue, thus appearing to form alternating bands. [8] These discrete plates are interconnected in longitudinal section.
The primary xylem of Stigmaria is endarch and arranged in a series of bands surrounded by vascular cambium. The secondary xylem tracheids are arranged in radial lines and contain scalariform wall thickenings with fimbrils identical to those in the aerial branches.
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.
Primary xylem is exarch upon maturation, with protoxylem strands positioned around the tips of the primary xylem arms. No differentiation between fascicular and interfascicular regions of the secondary xylem is apparent, and ray cells are rarely observed.
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 transporting tissue, formed of more than one cell type, found in vascular plants. The primary components of vascular tissue are the xylem and ...
The endodermis does not allow gas bubbles to enter the xylem and helps prevent embolisms from occurring in the water column. [ 2 ] Passage cells are endodermal cells of older roots which have retained thin walls and Casparian strips rather than becoming suberized and waterproof like the other cells around them, to continue to allow some ...
3- Water moves from the xylem into the mesophyll cells, evaporates from their surfaces and leaves the plant by diffusion through the stomata. In plants, the transpiration stream is the uninterrupted stream of water and solutes which is taken up by the roots and transported via the xylem to the leaves where it evaporates into the air/ apoplast ...