{"id":1522,"date":"2022-01-23T15:15:02","date_gmt":"2022-01-23T14:15:02","guid":{"rendered":"https:\/\/michelecrevecoeur.ch\/?page_id=1522"},"modified":"2022-01-23T15:15:36","modified_gmt":"2022-01-23T14:15:36","slug":"urtica-stem","status":"publish","type":"page","link":"https:\/\/michelecrevecoeur.ch\/?page_id=1522","title":{"rendered":"Urtica Stem"},"content":{"rendered":"\t\t
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Cross section through a stem of Urtica<\/strong><\/span><\/p>

The nettles are a genus from Urticaceae family which includes about thirty species of herbaceous plants with hairy leaves and a quadrangular stem. Micrographs below illustrate a paraffin cross section (10 \u00b5m thick) through a portion of stem fixed with FAA and stained with Astra blue \u2013 basic fuchsin.<\/span><\/p>

General aspect of the section. Central part of the pith has disappeared and appears as a large lacuna (star) and the stem is hollow. The vascular tissues (fc) are distributed on a single ring at the periphery of the pith, with xylem and phloem superposed. Xylem vessels are located towards the center and the phloem towards outside (characteristics of a young dicotyledon stem). Trichomes are observed at the epidermis level (blue arrow).<\/span><\/p>

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Part of the section. From the center towards outside we successively find: primary xylem (x1); secondary xylem\u00a0(x2)<\/span>, a few layers of rectangular cells corresponding to cambium ( c), secondary and primary phloem (phl2 and phl1, cortical parenchyma (par); the angular collenchyma\u00a0(co)<\/span>\u00a0constituted of thick \u2013 walled cells and the epidermis.<\/span><\/p>

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Portion of periphery of the stem section: uniseriate epidermis (ep) with trichomes (blue arrow on the left), a few rows of collenchyma\u00a0(co)<\/span>\u00a0with thick walls very apparent in corners of cells and the cortical parenchyma with small intercellular spaces.<\/span><\/p>

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Cross section through a stem of Urtica The nettles are a genus from Urticaceae family which includes about thirty species of herbaceous plants with hairy leaves and a quadrangular stem. Micrographs below illustrate a paraffin cross section (10 \u00b5m thick) through a portion of stem fixed with FAA and stained with Astra blue \u2013 basic […]<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"site-sidebar-layout":"no-sidebar","site-content-layout":"page-builder","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"disabled","ast-breadcrumbs-content":"","ast-featured-img":"disabled","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"class_list":["post-1522","page","type-page","status-publish","hentry"],"yoast_head":"\nUrtica Stem - 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