Chapter 23BIO 392

Floweringplants

Cone-bearingplants

Ferns andtheir relatives

Mosses andtheir relatives

Green algaeancestor

Flowers; SeedsEnclosed in Fruit

Seeds

Water-Conducting(Vascular) Tissue

PLANT STRUCTURE

Remember…• Organisms are

made up of:– Organ

Systems– Organs– Tissues– Cells

• Plants are made up of:• Organ Systems• Organs: Roots, Stems, Leaves• Tissues: Dermal, Vascular,

Ground, Meristematic• Cells: epidermal cells,

tracheids, vessel elements, sieve tube elements, companion cells, parenchyma, collenchyma, sclerenchyma,

Concept Map

include

includes includes includes

includes includes

Section 23-1

Plant Tissues

Dermaltissue

Meristematictissue

Vasculartissue

Groundtissue

Epidermalcells Xylem Phloem Parenchyma

cellsCollenchyma

cellsSchlerenchyma

cells

Tracheids Vesselelements

Sieve tubeelements

Companioncells

PLANT TISSUE SYSTEMS (4)A) MERISTEMATIC Source of new growth

for the entire life of the plant• Primary Growth plants grow taller and

deeper– Only in tips of roots & shoots– Apical meristem “the bud”

• Secondary Growth plants grow wider– Lateral Meristem tissue– (Also known as: vascular or cork cambium)

PLANT TISSUES cont.B) DERMAL TISSUE The outer covering of the

plant, “the skin”– May have waxy covering to prevent water loss

C) VASCULAR TISSUE transports fluids & nutrients throughout the plant,

“the bloodstream”– Xylem transports water– Phloem transports food (sugars made)

D) GROUND TISSUE everything else

3 Plant Organs

• Roots• Stems• Leaves

ROOTSFUNCTION

1. Absorbs water & dissolved nutrients from soil2. Anchors plant & prevents erosion

TYPES:1. Taproots long & thick,

2. Fibrous roots thin & branching

ROOTS cont.STRUCTURE (by tissue)

& TRANSPORT

1. Outer epidermal layera. covered by tiny root hairs – more S.A.b. contain active transport proteins in their cell membranes to pump minerals from soil into plant.c. water follows by osmosis

ROOT STRUCTURE cont.2. Large layer of Ground tissue

a. spongy cortexb. endodermis encloses vascular tissue

i. cells are surrounded by Casparian strips- waterproof barriers that force water

to go through cells, not around.

- Keep flow one way (osmosis)3. Central Vascular cylinder

a. water moves into the xylem b. because it cannot go backward, the only place

to go is up the stemi. “Root Pressure”

STEMSFUNCTION

1. Support; hold leaves up in the sunlight2. Transport substances between roots & leaves

TRANSPORT1. Capillary Action

a. water moves by cohesion from roots b. 1 way

2. Nutrients are transported through stema. in phloemb. in 2 directions

LEAVESFUNCTION

1. Site of Photosynthesis

STRUCTURE1. epidermis is covered by cuticle

a. reduce evaporation2. Mesophyll – specialized ground tissue

a. lots of chloroplastsb. where photosynthesis occurs

3. Veins of xylem & phloem branch

LEAVES cont.SPECIAL STRUCTURES

1. Stomata exterior openings on underside of leaf. Site of gas exchange (pores)a. O2 out b. CO2 inc. water vapor out

2. Guard cells surround and control stomata openings

LEAVES cont.TRANSPORT

1. Water escapes through stomataa. process of transpiration (evaporation)b. as water exits, more is drawn up

through stem from roots2. Stomata open and close to prevent excessive water loss.

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Shoots and Roots

Stem

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