Plant Tissue Systems

Ground tissue system• Photosynthesis, storage, and structural support of

other tissues

Vascular tissue system• Distributes absorbed water and mineral ions and

products of photosynthesis

Dermal tissue system• Covers and protects exposed plant surfaces

Body Plan: Tomato Plant

•Shoot system: above ground

•Stems, leaves, flowers•Root system: below ground

Apical and Lateral Meristems

•Apical meristem: located at tips of shoots and roots

•Primary growth•Lengthening

•Lots of mitosis•Lateral meristem: secondary growth

•Thickening

Vascular Tissues•Xylem: transports water

•Two cell types: tracheids and vessel elements•Hollow, nonliving

•Phloem: transports sugars•Cells called sieve tubes•Living

Dermal Tissues

Epidermis• Usually a single outer layer of cells that secrete a

waxy, protective cuticle• May contain specialized cells that form stomata

for gas exchange

Eudicots and Monocots

Flowering plants are divided into two classes with tissues organized into different patterns

Eudicots have two cotyledons (seed leaves)• Netlike leaf veins• Floral parts in multiples of 4 and 5

Monocots have one cotyledon• Parallel leaf veins• Floral parts in multiples of 3

Inside the Stem

Vascular bundles• Multistranded cords of vascular tissues threaded

lengthwise through ground tissues of all shoots Two distinct patterns of vascular bundles• Eudicot stems: Cylinders run parallel with stem,

divide ground tissue into cortex and pith• Monocot stems: Bundles distributed throughout

ground tissue

Root Structures

Divided into four general regions• Root Cap: protects root

as it lengthens• Region of Cell

Division: apical meristem

• Region of Elongation: cells lengthen and widen

• Region of Maturation: mature cells differentiate into different types

•Root hairs: increase the surface area for water and nutrient uptake

•Derived from epidermis

Internal Root Structures

Epidermis: covers exposed surfaces Cortex: cells adjacent to the epidermis • Used for food storage

Vascular tissues: xylemand phloem• Form the vascular cylinder

Endodermis: single cell layer around the vascular tissues• Aids in mineral/water exchange

Pericycle: undifferentiated cells• Source of new lateral roots

Eudicot and Monocot Root Structures

You will look at cross section slides of a monocot and a eudicot root.

Notice the star shape xylem and phloem in between the points on the eudicotLook for the pith in the monocot, used for food storage.

Root Systems

Taproot Fibrous root

Modified Stems

Many plants have modified stem structures that function in storage or reproduction• Stolons (reproductive runners)• Rhizomes (main underground storage stems)• Bulbs (layered underground stems)• Corms (solid underground storage stems)• Tubers (stolons thickened for storage)

Leaf Shapes

•Simple leaf: single blade•Compound leaf: blade with leaflets

•Palmately: leaflets attached at one point•Pinnately: leaflets attached at intervals

Leaf Structure

•Epidermis: outermost layer of cells

•Lower and upper•Cuticle: waxy, protect, conserve H2O•Palisade mesophyll: upper, many chloroplasts•Spongy mesophyll: lower, air spaces•Stomata: openings for gas exchange•Guard cells: surround stomata and control

Vein Patterns in Flowering Plants