Plant Evolution and Classification • Preventing Water Loss • Reproducing by Spores and Seeds • Transporting materials throughout the plant.
Classifying Plants • 2 groups based on the presence of vascular tissue • Nonvascular Plants • Vascular Plants • Seedless-fern like • Seeded- Maples, and Pine
Classification • Nonvascular Plants • Phylum Bryophyta • Phyla Haptophyta and Anthocerophyta
Seedless Vascular Plants • Phylum Psilotophyta • Phylum Lycophyta • Phylum Sphenophyta • Phylum Pterophyta
Vascular Seed Plants • Gymnosperms • Phylum Cycadophyta • Phylum Ginkgophyta • Phylum Gnetophyta • Phylum Coniferophyta • Angiosperms • Phylum Anthophyta
Monocot On cotyledon Parallele Venation Scattered Flower parts in 3’s Fibrous Dicot 2 cotyledons Net venation Radially arranged vascular bundles Flower parts in 4 and 5 Taproot Classes of Angiosperms
Plant Structure and Function • Plant Cells • 3 types • Parenchyma • Collenchyma • Sclerenchyma
Parenchyma • Loosely packed cube-shaped or elongated cells that contain large central vacuole. • Metabolic functions, photosynthesis and storage of water and nutrients. • Example~ Fleshy part of an apple
Collenchyma Cells • Thicker cell walls, irregular shape • Usually grouped in strands and are specialized for supporting regions that are still growing. • Celery
Sclerenchyma Cells • Thick rigid cell walls. • Support and strengthen the plant in areas where growth is no longer occurring. • Gritty texture of a pear fruit.
Tissue Systems • Dermal Tissue • Ground Tissue • Vascular Tissue
Dermal Tissue • Forms the outer coverings in plants • Consists of the epidermis, the outer layer made of parenchyma cells. • Roots~ absorption, protection • Stems~ gas exchange, protection • Leaves, gas exchange, protections.
Ground Tissue • All 3 cell types • Storage, metabolism and support.
Vascular Tissue • Functions in transport and support • Xylem-dead • Phloem-living • 2 major components for xylem • Tracheid • Vessel Element
Tracheid • Long thick walled sclerenchyma cell with tapering ends. • Water moves from on tracheid to another through piths
Vessel Element • A sclerenchyma cell that has either large holes in the top and bottom or no end wall at all. • Stacked to form long tubes called vessels.
Sieve Tube Member • Conducting parenchyma cells of angiosperm phloem. • Compounds move from one to another through sieve plats. • Each cell has a companion cells, specialized parenchyma cell.
Growth in Meristems (Primary Growth) • Meristem- regions where cells continuously divide for plant growth. • Apical Meristem- located in the tips of stems and roots. • Intercalary meristems- growth between the nodes of plants.
Root Structures • Root Cap • Covering of cells that protects the apical meristem. • Produces a slimy lubricant. • Root Hairs • Extensions of the epidermal cells. • Increase the surface area.
Primary Growth in Roots • Roots increase in length • cell division • elongation • maturation in the root tip • Dermal tissue matures to form the epidermis • Ground tissue matures into 2 regions • Cortex and Endodermis
Cortex • Located just inside the endodermis. • Largest region of the primary root. • Parenchyma cells
Endodermis • Inner cylinder of the cortex. • Vascular tissue in roots matures to form the innermost cylinder • Dicots and gymnosperms~ xylem makes of the central core of the root.
Primary Growth in Stems • Apical meristems give rise to the dermal, ground and vascular tissue. • Dermal- epidermis • Ground- cortex and pith • Cortex- just inside the epidermis • Pith- located in the center of the stem. • Vascular- xylem and phloem
Secondary Growth • Conifers and Woody dicots • Increases in girth or lateral dimension • Occurs at lateral meristems • Vascular cambium • Gives rise to secondary xylem and phloem • Cork cambium • Gives rise to bark
Vascular Cambium • Cells on the outside differentiate into phloem • Cells on the inside differentiate into xylem • Only new xylem transports water. • Older xylem located at the center is only for support.
Monocot Leaf Upper Epidermis Mesophyll Lower Epidermis Xylem Phloem
Dicot Leaf Upper Epidermis Xylem Palisade Mesophyll Spongy Mesophyll Phloem Lower Epidermis Guard Cells with Somata
Leaf Structures • Epidermis • Palisade Mesophyll • Spongy Mesophyll • Guard Cells • Vascular Bundles
Epidermis • A protective covering of one or more layers of cells. • Covered by the cuticle • Cutin • Transpiration
Palisade Mesophyll • Parenchyma cells • Numerous chloroplasts
Spongy Mesophyll • Parenchyma cells • Loosely arranged • Air spaces allow for gas exchange
Guard Cells • Specialized epidermal cells that control the opening and closing of stomata. • Controls gas exchanges with the environment.
Vascular Bundles • Consists of xylem and phloem tissues • Contains bundle sheath cells that prevent gas from entering the vascular bundle.
Transport of Water • Water and dissolved minerals enter the roots through root hairs by osmosis. • 2 Possible Pathways • Apoplast • Symplast
Apoplast • Water moves through cell walls from one cell to another without every entering the cells.