Plant Form

Chapter 36

Plant Classes

• Seed producing plants:– Gymnosperms– Angiosperms

• Dicotyledons (dicots)

• Monocotyledons (monocots)

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Plant Classes

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Plant Body Organization

All vascular plants consist of:

• Root system

• Shoot system

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• 3 basic tissue types

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DermalGround

Vascular

Plant Growth

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• Adult cell growth is limited.• Growth and development of adult plants is dependent on specialized cells called meristems.

Apical Meristem• Located at tips

of stems and roots.

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Lateral Meristem

• Produce wood and bark in trees and bushes – called secondary growth.

Vascular Tissue - Xylem

• Main water-transportation tissue

• Also transports dissolved minerals, NO3

and PO4.

• Provides stem support.

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• Principal food-conducting tissue in vascular plants

• Carries glucose and starch created during photosynthesis

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Vascular Tissue - Phloem

Roots

• Four regions are commonly recognized:

– Root cap

– Zone of cell division

– Zone of elongation

– Zone of maturation

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Stages in the differentiation of plant tissues

Modified Roots

• Most plants produce either/or:– Taproot system – single large root with small

branch roots– Fibrous root system – many small roots of

similar diameter– Some plants, however, produce modified

roots with specific functions– Adventitious roots arise from any place other

than the plant’s root

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Prop roots Aerial roots

Pneumatophores Water storage roots

Buttress roots

Stems

• Undergo growth from cell division in apical and lateral stems

• Shoot apical meristem cells create stem tissue as well as leaves, other shoots, and flowers.

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Parts of the Stem

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Monocot stemEudicot (Dicot) stem

Leaves

• Principal site of photosynthesis

• Expand by cell division and cell enlargement

• Growth stops at maturity

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Leaf Structure

•Cuticle•Epidermis•Palisade mesophyll•Spongy mesophyll•Vascular bundles•Guard cells•Stoma

Modified Leaves

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Bracts

Spines

Insectivorous

Reproductive