Chapter 43 BSC 1005 Tidwell Plant Anatomy and Nutrient Transport The root system consists of all the roots of a plant The shoot system is usually located aboveground Roots are branched portions of the plant body that carry out six major functions o Anchor the plant in the ground o Absorb water and minerals plant nutrients from the soil o Store surplus food principally carbohydrates that were manufactured in the shoot during photosynthesis o Transport water minerals sugars and hormones to and from the shoot o Produce some hormones o Interact with soil fungi and bacteria that help provide nutrients to the plant The shoot system consists of buds leaves flowers and fruits all borne on various parts of stems Flowering plants angiosperms can be divided into two groups o Monocots include lilies daffodils tulips palm trees and a wide variety of grasses not only the familiar lawn grasses but also wheat rice corn oats and bamboo o Dicots bushes most vegetables and many flowers in fields and gardens include virtually all broad leafed plants including deciduous trees and A cotyledon is the part of a plant embryo that absorbs and often stores food reserves in the seed and then transfers the food to the rest to the embryo when the seed sprouts Plants are composed of two types of cells o Meristem cells like the stem cells of animals are unspecialized and are capable of mitotic cell division Some of their daughter cells lose the ability to divide and become differentiated cells with specialized structures and functions Apical meristems tip meristems are located at the tips of roots and shoots Growth produced by apical meristem cells is called primary growth an increase in the height or length of a shoot or root and the development of specialized parts of the plant such as leaves and buds Lateral meristems side meristems also called cambium are concentric cylinders of meristem cells much like small diameter pipes nested within pipes of larger diameter Secondary growth is typically an increase in the diameter and strength of roots and shoots As meristem cells differentiate they produce a wide variety of cell types o The dermal tissue system covers the outer surface of the plant body Page 1 of 5 Chapter 43 BSC 1005 Tidwell is the outermost cell layer covering the leaves stems and Epidermis roots of all young plants Epidermal tissue also covers flowers seeds and fruit The epidermal tissue of the aboveground parts of a plant is generally covered with a waterproof waxy cuticle secreted by the epidermal cells The cuticle reduces the evaporation of water from the plant and helps protect it from the invasion of disease microorganisms replaces epidermal tissue on the roots and stems of woody Periderm plants as they age Periderm is composed primarily of multiple layers of cork cells on the outside of the root or stem and a layer of lateral meristem tissue called the cork cambium o The ground tissue system makes up most of the body of young plants its functions include photosynthesis storage and support The three types of ground tissues are parenchyma collenchyma and sclerenchyma Parenchyma the most abundant ground tissue makes up most of the body of a young plant Parenchyma cells have thin cell walls and are alive at maturity They typically carry out most of the plant s metabolic activities including photosynthesis most of the cells of a leaf are parenchyma cells secretion of hormones and food storage Potatoes seeds fruits and storage roots such as carrots are packed with parenchyma cells that store various types of sugars and starches o Parenchyma cells also help to support o Some parenchyma cells can divide o Parenchyma cells are found in periderm and vascular tissues Collenchyma with thickened but still flexible cell walls tissue consists of cells that are typically elongated o Collenchyma cells are alive at maturity but generally cannot divide o Collenchyma tissue provides support Celery stalks which are actually extremely thick petioles are supported by strings composed mostly of collenchyma cells tissue is composed of cells with thick hardened cell Sclerenchyma walls o Sclerenchyma cells support and strengthen the plant body however unlike collenchyma they die after they differentiate Their thick cell walls then remain as a source of support Page 2 of 5 Chapter 43 BSC 1005 Tidwell o The vascular tissue system transports fluids throughout the plant body The vascular tissue system consists of two conducting tissues xylem and phloem transports water and dissolved minerals only in one Xylem direction from the roots up to all parts of the shoot system o In angiosperms xylem contains supporting sclerenchyma fibers and two specialized conducting cell types tracheids and vessel elements o Both tracheids and vessel elements develop thick cell walls and then die as their final step of differentiation leaving behind hollow tubes of nonliving cells wall are thin elongated cells stacked atop Tracheids one another Vessel elements tracheids form pipelines called vessels transports sugars and other organic molecules which are larger in diameter than o Phloem consists mainly of two cell types sieve tube elements and companion cells Sieve tube elements pipes called sieve tubes are joined end to end to form Phloem throughout the plant body Life support of sieve tube elements is provided by smaller adjacent companion cells which are connected to sieve tube elements by pores called plasmodesmata The junction between two sieve tube elements is called a sieve plate Leaves are the major photosynthetic structures of most plants o The essentials for photosynthesis are sunlight carbon dioxide CO2 and water o A typical angiosperm leaf consists of a broad flat portion the blade connected to the stem by a stalk called the petiole o The epidermis and cuticle are pierced by adjustable pores the stomata singular stoma which regulate the diffusion of CO2 O2 and water vapor into and out of the leaf o The transparent epidermal cells allow sunlight to reach the mesophyll middle of the leaf which consists of loosely packed cells containing chloroplasts o Vascular bundles in leaves also called veins containing xylem and phloem conduct materials between the leaf and the rest of the plant body The stems of the plant shoot system support and separate the leaves lifting them into the sunlight and air o The petiole of a leaf is attached to the stem at a location called a node Page 3 of 5 Chapter 43 BSC 1005 Tidwell As most dicot shoots grow