Plant Structure Chapter 35

Angiosperms Monocots Seed one cotyledon (seed leaf) Leaves parallel veins Roots fibrous Vascular tissue scattered Flower parts 3’s or multiples of 3’s Bulbs, grasses, grains, orchids

Angiosperms Dicots (eudicots) Seed with 2 cotyledon (seed leaf) Leaves with network of veins Taproot Vascular tissue arranged in a ring Flowers in groups of 4 & 5 or multiples Annuals, trees, shrubs, roses, peas

Angiosperms

Plant cells 1. Parenchyma cells Large vacuoles Thin walled Make & store organic products Fleshy tissue of most fruit

Plant cells 2. Collenchyma cells Support organs Allows stems to bend & not break

Plant cells 3. Sclerenchyma cells Supporting elements of plant More rigid

4.Water-conducting cells Xylem Move water & minerals Vessel members (elements) Continuous tubes Tracheids Tapered ends Thick walled Wood is secondary xylem

Xylem

5. Sugar-conducting cells Phloem Sieve cells Sieve-tube members (elements) Conduct carbohydrates Move away from where formed (source) To where needed or stored (sink)

5. Sugar-conducting cells Companion cells: Next to sieve-tube cells Plasmodesmata: Connection between cells

Phloem

Tissue types 1. Dermal tissue Epidermis (primary growth) One cell layer thick Outer protective layer Cuticle wax cover-water loss Periderm (secondary growth) Replaces epidermis in woody plants

Dermal tissue Trichomes Shoot epidermis “fuzzy” Minimize evaporation Plant defense

Dermal tissue Root hairs Behind root tips Increase surface area Absorption

Tissue type 2. Vascular tissue Transport Xylem & phloem 3. Ground tissue Parenchyma cells Storage, photosynthesis, support

Tissues

Organs Root Stem Leaves

Root Anchors the plant Absorbs nutrients Water & ions

Roots Tap root One large root with small roots Lateral root Branched roots Adventitious root Root grows from another part of plant Fibrous root Mat of thin roots

Root

Root

Root

Lateral roots

Stem Positions & supports leaves Node: Leave attachment Internode: Area on stem between nodes

Stem Terminal bud: Bud at end where apical meristem Axillary bud: Bud along stem may be a branch

Leaf Extension of shoot Photosynthesis Blade (flattened) Stalk (petiole) mostly eudicots

Leaf Stomata: Tiny pores Guard cells: Specialized epidermal cells Regulate opening Transpiration: Evaporation of water

Leaf Surface covered with epidermis Mesophyll: Ground tissue Between epidermis layers Contains veins (vascular bundles)

Leaf Palisade mesophyll: Closest to upper epidermis Tightly packed cells Chloroplasts Spongy mesophyll: Loosely arranged Contains air spaces

Leaf

Growth Meristems: Embryonic tissues Similar to stem cells One cell remains meristematic Give rise to other tissues Apical meristems Cell division Elongation of roots & stems (tips)

Meristems

Fig. 35.18 Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Growth

Secondary growth Secondary tissues: Lateral meristems Vascular cambium (xylem-wood, phloem) Cork cambium Secondary growth-increases girth

Secondary growth

Stem Fig. 35.22 Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings