Plant Organs: Stems PDF

Plant Organs: Stems www.usask.ca Stem § Primary functions of the stem are: support t ranslocation photosynthesis storage Support § The stem’s basic function is to support the ___________________ green tissues (leaves)...

Plant Organs: Stems www.usask.ca Stem § Primary functions of the stem are: support t ranslocation photosynthesis storage Support § The stem’s basic function is to support the ___________________ green tissues (leaves) + flowers § Many stems are ___________ erect ↑ § A ________________ twining set stem uses other plants or structures for support. § Stems can also be _____________ prostrate meaning they grow along the ground. Translocation § Stems contain vascular bundles (xylem and phloem) that are responsible for movement of? Xylem transports water and dissolved nutrients Phloem transports food XYLEM > - H2O PHLOEM > - FOOD Photosynthesis § Green stems of plants may also be sites of __________________________ photosynthesis § In some plants the stem is the primary area of photosynthesis because the plant has poorly developed leaves. For example: · CACTUS WHEAT · PEA'S ·  SUGAR CANE Storage § Stems also can be modified for _______________ food storage § Some plant stems are used for food as they store large amounts of sugar. ASPARAGUS § Some vegetable stems are harvested at an immature state for food. How do stems grow and develop? § Stems contain _______________ meristem regions which develop leaves, branches, tillers, adventitious roots, and buds. ↑ BRANCHING IN MONOCOTS Node and Internodes § The stem is normally divided into nodes and internodes. § The internodes distance one node from another. ope Nodes and Internodes Dicot Stems § Dicot vascular bundles are arranged in a _____________________ circle around the central pith core. § Dicots have vascular cambium to increase the girth of the plant. § In dicots, a node is the place of attachment for one or more leaves as well as ___________ DUCS which can grow into branches. Dicot Stems 9 Monocot Stems § Monocots stems differ from dicots in that monocots do not have a lateral meristem (cambium) to increase girth. instead monocots increase the stem thickness by cell _____________________ expansion (not cell division). Monocot Stems § Monocot stems have vascular bundles __________________ scattered throughout the outer layer of pith. § Stems are _____________ hollow in many monocots. § Monocots have distinct nodes and internodes and nodes are ___________ solid § Leaves originate at the _____________ nodes § The intercalary meristem is at base of leaf. Monocot Stems NODE BLADE SHEATH Difference between Monocot and Dicot Stems *FINAL Monocot Dicot Method of Cell expansion (no cambium) Cell division in the cambium girth growth Vascular Scattered throughout the pith Arranged in a circle around the bundles layer (but often concentrated at central pith core. toward the outside of the stem). Nodes and Distinct sections of nodes and Stem sections less distinct in Internodes internodes. many species. Solid nodes. Stem usually filled with pith Internode section often hollow but not in all species. but may be filled with pith. Leaf attachment directly at Leaf attachment at nodes by node or by petiole. sheath. Tillering in Grasses (Monocots) § Most grasses have the ability to produce side shoots called _____________ tillers - tillering § The ability to produce tillers is controlled by genetics and environmental conditions. § For example 2 row barley will produce more tillers than 6 row types. Tillering g Control of Branching and Tillering § In dicots, the side shoots are referred to as branches. § __________________________________ environmental conditions also determines branching and tillering. § Increased branching/tillering occurs when plants are spaced farther apart due to increased light penetration. § Optimum supply of nutrients and water is also important. THEY (TILLERS) DONT ALL GROW & SAME TIME - If there is less than optimum amounts, there will be less branching/tillering. ABUNDANT TILLERING BAD > NOTALLAT = - SAME STAGE Apical Dominance in Dicots § Many dicot plants exhibit strong apical dominance. The _______ + Op of plant is the main point of growth. § Apical dominance is caused by hormones in the plant apex. This results in one stem being dominant and it controls the formation of branches from the buds along the stems.  TRYING TO CHOP THE TOP TAKE OVER : TAKEN Off Apical Dominance ↑ ! APEY § If the apex is V removed, it usually allows lower buds to develop more very unstable lateral branches. blc of § Undesirable to do dual in spruce trees as stem causes branching at point where this apex is removed. https://adairtreecare.com/posts/the-evil- weevil-pine-weevil-damage-in-calgary https://www.willmarradio.com/promotions/enter-your-tree-in-the-ugly-tree- contest-with-crows-nest-tree-service/article_1dd3142e-bcea-11ec-91de- 8fa26e5ae9c7.html#/rounds/1/gallery/329067559. minnesota  Copyright Sourcing Slide 1: Permission: Saskatoon, SK: University of Saskatchewan. Slide 3: Source: https://commons.wikimedia.org/wiki/File:Lapageria_rosea_twining.jpg Permission: CC BY 3.0 Courtesy of Vinesman [email protected] Slide 6: a) Source: https://commons.wikimedia.org/wiki/File:Sugar_cane_mauritius2_hg.jpg Permission: CC BY-SA 2.5 Courtesy of Hannes Grobe, AWI. b) Source: https://www.flickr.com/photos/sigfridlundberg/17357321205 Permission: CC BY-SA 2.0 Courtesy of Sigfrid Lundberg. Slide 9: Source: https://commons.wikimedia.org/wiki/File:Stem_nodes.svg Permission: CC BY-SA 3.0 Courtesy of Rugby471. Slide 11: Source: https://commons.wikimedia.org/wiki/File:Plant_nodes_c.jpg Permission: Public Domain. Courtesy of Knulclunk. Slide 14: Source: https://commons.wikimedia.org/wiki/File:Cinna_latifolia_(6081578216).jpg Permission: CC BY-SA 2.0 Courtesy of Matt Lavin from Bozeman, Montana, USA. Slide 17: Source: https://commons.wikimedia.org/wiki/File:Poaceae_tillers_and_new_shoot.jpg Permission: CC0 1.0 Public Domain. Courtesy of RoRo.