BIOL 3427 1st Edition Lecture 5Outline of Last Lecture I. Plant cell StructureCurrent LectureII. Secondary GrowthA. Occurs in stems and rootsB. Secondary meristema. Increases the width/girth of the plantIII. Vascular Cambiuma. Arises from procambial cellsb. Periderm replaces epidermis in woody rootsi. Usually factors initiation of secondary xylem and phloem by vascular cambiumc. Pericycle divides to produce complete cylinder of cork cambiumi. Cork towards outer surfaceii. Phelloderm towards inner surfaceiii. Outer periderm may have lenticels1. Spongy areas for gas exchange2. Once periderm formed, epidermis and cortex die ofa. Due to isolationIV. Origin of lateral rootsa. Usually originate in pericycle itselfb. Divisions occur same distance behind region of elongationV. Root primodium (Young root)a. Rootcap, apical meristem, primary meristems, develop earlyb. Vascular cylinders of lateral root and parent root connect laterVI. Adventitious rootsa. Come from somewhere else not the rootb. Arising from non-root tissueVII. Aerial rootsa. Arise from above ground tissue (Stem)b. May serve as prop roots for supportc. Function as normal roots upon soil contactd. May anchor to other surfaces for supportVIII.Our roots/ pneumatophoresThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.a. Roots growing upward from soil, against gravityb. Due to poor soil aerationc. Contain lenticels; lots of intercellular air space in cortexd. Examples of pneumatophoresi. Bald Cyprus “Knees”1. Growing in water logged soilsii. Epiphyte adaptations1. Plants that grow on top of other plants; used for anchoring or bringing in water nutrients2. Root epidermis may be several layers thick and may be photosynthetic3. Velamon (thick)a. Protectionb. Prevents water lossIX. Adaptations for food storage: fleshy rootsa. Storage parenchyma permeated by vascular tissueb. Some species (e.g carrot) have more parenchyma in secondary xylem and phloemc. Others develop additional cambia that produce more storage parenchyma (e.g sweet potato)X. Chapter 25: Primary Storage and Developmenta. Shooti. Definition-stem and its associated leavesii. More complex than root1. Shoot has nodes and internodes2. Rootcap: shoot apex produces leaves and axillary buds (bud sits in Axil of leaf)b. Internodes: between nodesc. Axel- Angle between stem and leafXI. Stem functionsa. Support for leavesb. Conduction of materialsXII. Apical Meristema. Adds cells to primary tissue plant bodyb. Produces: i. Leaf primordiaii. Bud primordiac. Phytomeresi. Organization of leaf, axillary bud, internode occurs all over againii. Includes leaf, Node, Internode, and axillary budiii. Repeat all the way down the shootiv. May be protected by young leavesXIII. Vegetative shoot apexa. Cannot be divided into zonesb. Leaf primordia originate too quickly to distinguish nodes and internodesc. Elongation of stem occurs primarily when internodes elongateXIV.Shoot Apical meristema. Gives rise to same primary meristemsi. Ground, procambium, protodermXV. Three basic organizationsa. Vascular system of internode is more or less continuous cylinder within ground tissuei. Some gymnosperms, magnoliids, eudicotsb. Bundles-root of vascular tissuei. Primary vascular tissues develop as ring of bundles separated by ground tissue1. Other eudicotsc. More complexi. Some non-woody herbaceous, most monocots1. 2+ rings of vascular bundles or scattered bundles2. Refer to figure 26-7 in textbookXVI. Structure of stema. Almost continuous vascular cylinderi. Tilia (Basswood, Linden)ii. Vascular bundles separated by very narrow area of ground parenchyma(interfascicular parenchyma)1. Epidermis (single layer of cells)a. Covered by cuticle –prevents water lossb. Usually few stomata2. Cortexa. Collenchyma (Support for young growing organs)b. Parenchyma- photosyntheticXVII. Vascular tissuea. Primary phloem develops from outer cells of procambiumb. Primary xylem from inner cellsc. One layer of cells in between becomes vascular cambium when secondary tissueoriginatesXVIII. Pitha. Parenchyma cells with large canals full of mucilageb. Intercellular air spacesXIX. Collenchymaa. Thickened cell wallsXX. Vascular system of discrete strandsa. Elder berry  bundles of vascular tissuei. Dicotii. Sambucuus (elderberry)1. Epidermis, cortex, pith, similar to Tilia; interfascicular regions (pithrays)a. Relatively wideb. When secondary growth initiates vascular cambiumdevelops from interfascicular parenchyma connecting toprocambium in bundlesb. Medicago (Alfalfa)i. Herbacious Eudicot with some secondary growthii. Similar to Sambucusc. Rununculus (Buttercup)i. Bundle structure: similar to Monocotsii. No procambium after primary vascular tissues mature1. Closed vascular bundles (no potential for further