4/3/2014 BI 103: Laboratory 1 Plant tissues & morphology Tissues & Organs I. Plants have three -four major groups of organs: 1. Roots 2. Stems 3. Leaves 4. Flowers II. Each organ is composed of tissues. A tissue is a group of cells performing a similar function. 1 4/3/2014 Plant Anatomy: Vegetative Organs Leaves: Stem: Arise from stem Place leaves, buds, & roots attach Roots: Arise from stem Plant Anatomy: Vegetative Organs Leaves: Stem: Photosynthesis Support Gas exchange Transport Light absorption Storage Roots: Anchorage Storage Form = Function Transport Absorption 2 4/3/2014 Kale Broccoli Wild Brassica oleracea Cauliflower Cabbage Kohlrabi Brussels sprouts Plant Organs: human cultivation and manipulation 3 4/3/2014 Plant Anatomy: Tissues 4 Tissues: 1. Meristematic 2. Ground 3. Vascular 4. Dermal Plant Growth Meristems – Tissues of plants that add new growth. Regions of actively dividing cells. Apical – increases length/height (primary) Lateral – increases girth. (secondary) 4 4/3/2014 Plant Anatomy: Tissues and Cells Meristematic Tissue Apical Pericycle Vascular Cork Meristem Cambium Cambium Functions of Meristematic Tissue: • Growth • Primary (length) • Secondary (girth) Apical Growth Root: pericycle Shoot: Apical meristem 5 4/3/2014 Apical Meristem Aka lateral buds Leaf Apical Primordia Meristem Older Leaf Primordia Axillary Bud (developing) Primordia 6 4/3/2014 Old Tjikko– can trees live forever? 9,550 yrs old root system Norway spruce in Sweden Trunk itself only ~700 yrs old Secondary Growth 7 4/3/2014 Types of Tissues Dermal tissue system – protects plant Ground tissue system – Vascular tissue – Tissues and Cells Epidermal Tissue Epidermis Guard Trichomes Root hairs Cells Functions of Dermal Tissue: • Protection • Regulates movement of materials Trichomes: 8 4/3/2014 Dermal Tissues I. Cuticle – waxy coating II. Epidermis – for outer layer III. Trichomes – Hairs for preventing water loss. IV. Periderm – outer bark V. Guard cells & Stomata Guard Cells 9 4/3/2014 Types of Tissues Dermal tissue system – protects plant Ground tissue system – Provides support, stores starch, and carries out photosynthesis. Vascular tissue – Tissues and Cells Ground Tissue Parenchyma Collenchyma Sclerenchyma Flexible Rigid Large cell Small Cell Thin cell wall Thickest cell wall Functions of Ground Tissue: • Support: water filled vacuoles • Storage: starch • Photosynthesis 10 4/3/2014 Ground tissue Parenchyma cells: • Majority of cells in the plant. • Thin, pliable walls • Large vacuoles and various secretions Parenchyma cells • These cells photosynthesize in leaves. • Living Tissues and Cells: Ground Tissue In Roots: Parenchyma Parenchyma contain extra In Leaf: starch in the In Stem: Mesophyll cells cortex for storage Parenchyma form Contain lots of pith for support chloroplasts for photosynthesis 11 4/3/2014 Ground tissue Collenchyma cells: • Cell walls moderately thick • Flexible support Collenchyma cells • Living cells Ground tissue Sclerenchyma tissue - • Thick, tough, secondary walls, normally impregnated with lignin Sclereids • Function in support • Dead at maturity Two types: • Sclereids - Stone Cells • Fibers- long and thin 12 4/3/2014 Sclereids Fibers: • Sclereids - Stone Cells • Fibers- long and thin Types of Tissues Dermal tissue system – protects plant Ground tissue system – Provides support, stores starch, and carries out photosynthesis. Vascular tissue – Conducts fluids and helps strengthen roots, stems and leaves. 13 4/3/2014 Tissues and Cells Vascular Tissue Tracheids Vessel Sieve Tube Companion Elements Members Cells Xylem Phloem Functions of Vascular Tissue: • Transport • Support Vascular Tissue I. Xylem – water & minerals conducting pipes. --Wood is mostly xylem, -- dead at maturity II. Phloem – transports sugars & hormones -- Sap runs through phloem 14 4/3/2014 Complex plant conducting tissues > xylem >phloem a young corn stem is shown here. Secondary Growth 15 .