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Primary xylem is formed during primary growth from procambium. It includes protoxylem and metaxylem. Metaxylem develops after the protoxylem but before secondary xylem. Metaxylem has wider vessels and tracheids than protoxylem. [citation needed] Secondary xylem is formed during secondary growth from vascular cambium.
Parenchyma is a versatile ground tissue that generally constitutes the "filler" tissue in soft parts of plants. It forms, among other things, the cortex (outer region) and pith (central region) of stems, the cortex of roots, the mesophyll of leaves, the pulp of fruits, and the endosperm of seeds.
[5] There are usually three basic types of protostele: haplostele – consisting of a cylindrical core of xylem surrounded by a ring of phloem. An endodermis generally surrounds the stele. A centrarch (protoxylem in the center of a metaxylem cylinder) haplostele is prevalent in members of the rhyniophyte grade, such as Rhynia. [6]
[1] Maturation Zone: Cells in this stage have developed differentiated characteristics and have completed maturation and elongation. The xylem system is seen to develop in this zone along with lateral root development. Elongation Zone: Cells in this stage are rapidly elongating and parts of the phloem system (sieve tubes) start to develop. As ...
Cross-section of a flax plant stem: 1. Pith 2. Protoxylem 3. Xylem I 4. Phloem I 5. Sclerenchyma 6. Cortex 7. Epidermis. In botany, a cortex is an outer layer of a stem or root in a vascular plant, lying below the epidermis but outside of the vascular bundles. [1]
This page was last edited on 14 May 2022, at 21:50 (UTC).; Text is available under the Creative Commons Attribution-ShareAlike 4.0 License; additional terms may apply ...
Xylem sap is mostly made of water. This is because one of the main roles of xylem is to transport water and inorganic nutrients throughout the plant. [13] Water is not the only thing that makes up xylem sap though. Xylem sap contains long-distance signaling hormones, proteins, enzymes, and transcription factors.
This is incorrect. Most clades of xylem-bearing plants lack vessel elements. The defining feature of xylem in recent cladistic and morphological literature seems to be the presence of the compound lignin, not a cell type. In fact, some of the "xylem" in the Silurian rhyniophytes has been found not to be true xylem, despite the structure of the ...