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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. In addition, there is also a tissue between xylem and phloem which is the cambium.
Types of Vascular bundles (black: Xylem, green: Phloem, white: Cambium) A concentric, periphloematic B concentric, perixylematic C radial with inner xylem, here with four xylem-poles, left closed, right open D collateral closed E collateral open F bicollateral openCross section of celery stalk, showing vascular bundles, which include both phloem and xylemDetail of vascular bundle: closed, collateral vascular bundles of the stem axis of Zea maysVascular bundle in the leaf of Metasequoia glyptostroboidesThe vascular bundle of pine leaf showing xylem and phloem
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. In a leaf, the adaxial surface of the leaf will usually be the upper side, with the abaxial surface the lower side.
The sugars synthesized by the plant with sun light are transported by the phloem, which is closer to the lower surface. Aphids and leaf hoppers feed off of these sugars by tapping into the phloem. This is why aphids and leaf hoppers are typically found on the underside of a leaf rather than on the top. The position of vascular bundles relative to each other may vary considerably: see stele.
Cross section of a leaf showing parts of a vascular bundle
The bundle-sheath cells are the photosynthetic cells arranged into a tightly packed sheath around the vein of a leaf. It forms a protective covering on leaf vein, and consist of one or more cell layers, usually parenchyma. Loosely arranged mesophyll cells lie between the bundle sheath and the leaf surface. The Calvin cycle is confined to the chloroplasts of these bundle sheath cells in C4 plants. C2 plants also use a variation of this structure.[1]
ReferencesEdit
^Sage, Rowan F.; Khoshravesh, Roxana; Sage, Tammy L. (1 July 2014). "From proto-Kranz to C4 Kranz: building the bridge to C4 photosynthesis". Journal of Experimental Botany. 65 (13): 3341–3356. doi:10.1093/jxb/eru180.
Further readingEdit
Campbell, N. A. & Reece, J. B. (2005). Photosynthesis. Biology (7th ed.). San Francisco: Benjamin Cummings.
External linksEdit
Curtis, Lersten, and Nowak cross section of a vascular bundle
Mauseth another cross section of a vascular bundle
October 17, 2023
vascular, bundle, help, expand, this, article, with, text, translated, from, corresponding, article, french, february, 2019, click, show, important, translation, instructions, view, machine, translated, version, french, article, machine, translation, like, dee. You can help expand this article with text translated from the corresponding article in French February 2019 Click show for important translation instructions View a machine translated version of the French article Machine translation like DeepL or Google Translate is a useful starting point for translations but translators must revise errors as necessary and confirm that the translation is accurate rather than simply copy pasting machine translated text into the English Wikipedia Consider adding a topic to this template there are already 5 799 articles in the main category and specifying topic will aid in categorization Do not translate text that appears unreliable or low quality If possible verify the text with references provided in the foreign language article You must provide copyright attribution in the edit summary accompanying your translation by providing an interlanguage link to the source of your translation A model attribution edit summary is Content in this edit is translated from the existing French Wikipedia article at fr Faisceau cribro vasculaire see its history for attribution You should also add the template Translated fr Faisceau cribro vasculaire to the talk page For more guidance see Wikipedia Translation 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 In addition there is also a tissue between xylem and phloem which is the cambium Types of Vascular bundles black Xylem green Phloem white Cambium A concentric periphloematic B concentric perixylematic C radial with inner xylem here with four xylem poles left closed right open D collateral closed E collateral open F bicollateral openCross section of celery stalk showing vascular bundles which include both phloem and xylemDetail of vascular bundle closed collateral vascular bundles of the stem axis of Zea maysVascular bundle in the leaf of Metasequoia glyptostroboidesThe vascular bundle of pine leaf showing xylem and phloemThe 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 In a leaf the adaxial surface of the leaf will usually be the upper side with the abaxial surface the lower side The sugars synthesized by the plant with sun light are transported by the phloem which is closer to the lower surface Aphids and leaf hoppers feed off of these sugars by tapping into the phloem This is why aphids and leaf hoppers are typically found on the underside of a leaf rather than on the top The position of vascular bundles relative to each other may vary considerably see stele Cross section of a leaf showing parts of a vascular bundle Contents 1 Bundle sheath cells 2 References 3 Further reading 4 External linksBundle sheath cells EditThe bundle sheath cells are the photosynthetic cells arranged into a tightly packed sheath around the vein of a leaf It forms a protective covering on leaf vein and consist of one or more cell layers usually parenchyma Loosely arranged mesophyll cells lie between the bundle sheath and the leaf surface The Calvin cycle is confined to the chloroplasts of these bundle sheath cells in C4 plants C2 plants also use a variation of this structure 1 References Edit Sage Rowan F Khoshravesh Roxana Sage Tammy L 1 July 2014 From proto Kranz to C4 Kranz building the bridge to C4 photosynthesis Journal of Experimental Botany 65 13 3341 3356 doi 10 1093 jxb eru180 Further reading EditCampbell N A amp Reece J B 2005 Photosynthesis Biology 7th ed San Francisco Benjamin Cummings External links EditCurtis Lersten and Nowak cross section of a vascular bundle Mauseth another cross section of a vascular bundle Retrieved from https en wikipedia org w index php title Vascular bundle amp oldid 1137387157, wikipedia, wiki, book, books, library,
