Plant Form and Function ALCOS Objective 4 and 5

Objectives Identify the three basic cell types Describe the histology of roots, stems, leaves and flowers

Introduction Major differences between plant and animal cells Presence of cell wall Presence of chloroplast and chlorophyll Presence of large, central vacuole

Plant Cells Three basic plant cell types (Figure 23.2) Parenchyma - food storage and production, contain numerous chloroplast Collenchyma - strength and support Sclerenchyma - strength and support, dead at maturity

Plant Tissue Four basic plant tissue types Dermal Tissue (Figure 23.4) Provides covering and protection Contain a waxy cuticle designed to help prevent water loss Stomata Openings in plant leaf that control the exchange of gases Root-hairs Extensions of individual cells that help roots absorb water and minerals Trichomes Epidermal hairs that help reduce evaporation from plants

Plant Tissue Four basic plant tissue types Vascular Tissue Xylem – transports water and minerals from the roots to the rest of the plant Phloem – transports sugars and other compounds throughout the plant Ground Tissue Found throughout the plant F(x): photosynthesis, storage and support

Plant Tissue Four basic plant tissue types Meristematic Tissue Meristems Regions of actively dividing cells Apical Meristem – increase plant length Lateral Meristem – increase plant diameter Vascular Cambium – produces xylem and phloem Cork Cambium – produces bark

Plant Tissue

Plant Organs Root – plant organ that anchors a plant a absorbs water and dissolved minerals Four basic root types Taproot – found in carrots Fibrous – found in grasses Proproot – found in corn and mangroves Pneumatophore – found in bald cypress

Plant Organs

Plant Organs Stem above ground portion of the plant that supports the leaves and flowers Secondary Growth Increases diameter Primary Growth Increases length Five stem types Herbaceous – petunia Woody – trees and shrubs Corm – gladiolus Tuber – potato Rhizome – iris, ferns

Plant Organs

Plant Organs

Plant Organs Leaf Plant organ used for capturing sunlight Simple Leaf – blade not divided Compound Leaf – blade divided into leaflets Leaf arrangement Whorled, Alternate, Opposite

Plant Organs Leaf Leaf composed of Mesophyll Tissue Photosynthetic plant tissue made of parenchyma cells Modified leaf types Spine – reduces water loss, provides protection (Cacti) Tendril – helps plant climb, cling to surface of materials (Vines)

Flower Flower Complex structure made of organs involved in fertilization and seed production All flower share same four basic structures Petals Sepals Stamen Pistil

Flower Petals Colorful structures at the top of a flower stem (Peduncle) Often with perfume or nectar at their base to attract pollinators

Flower Sepals Leaf-like, encircle the peduncle below the petals Provide protective covering for the flower bud May be colored

Flower Stamen Male reproductive structure Anther Filament Found at the tip of the stamen Produces pollen Filament Stalk that supports the anther

Flower Pistil Female reproductive organ Stigma Style Ovary Receives the pollen Style Stalk that connects the stigma to the ovary Ovary Contains one or more ovules Each ovule contains one egg cell

Flower Complete Flower Incomplete Flower Photoperiodism Pollination Contain all four major flower organs Petal, Sepal, Stamen, Pistil Incomplete Flower Lack one or more major flower organs Photoperiodism Response of flowering plants to daily daylight- darkness patterns Pollination Transfer of pollen from the anther to the stamen Maybe pollinated by wind, water or animals

Flower

Flower

Flower