Plant Structures Roots, Stems, and Leaves Chapter 23

Plants Roots Stems Leaves Seed plants have three main structures: Linked together by various means

Function of Roots Roots Absorb/Transport water and nutrients Anchor plant to the ground Hold soil in place and prevent erosion Storage of sugars made In photosynthesis

Functions of Stems Stems Support for the plant body Carries nutrients throughout plant

Functions of Leaves Leaves Main photosynthetic systems Sight of gas exchange

Tissues in Plants Dermal tissue Vascular tissue Ground tissue

Tissues in Plants 1. Dermal Tissue Cuticle Outer covering – waxy coating Roots have dermal tissue Root hairs Stomata and Guard cells within

Tissues in Plants 2. Vascular Tissue Xylem Phloem Transport System V for vascular, V for vein! 2. Vascular Tissue Transport System Carries water and nutrients. Xylem (Water in) Phloem (Glucose out)

Tissues in Plants 3. Ground Tissue Cells between dermal and vascular tissue

Taproots Fibrous roots *Roots Types of Roots Long, thick root Reach deep into the soil to obtain water/nutrients Fibrous roots Many thin roots Spread out away from plants to find water and nutrients quickly Helps to reduce erosion of soil Taproot Fibrous root

Roots Anchor plant Absorb water/nutrients Storage of sugar Root Functions Anchor plant Absorb water/nutrients Storage of sugar

Stems Functions Produce leaves, branches, and flowers Hold leaves up Transport substance between roots and leaves

Stems 2 types of stems Herbaceous Woody

Stems Xylem and phloem Transport water and nutrients Contain nodes – attachment for leaves

Leaves Function Photosynthesis Covered by: epidermis and cuticle Main site of: Photosynthesis Covered by: epidermis and cuticle Create water proof barrier

Leaves 1. Palisade mesophyll 2. Spongy mesophyll -some photosynthesis Mesophyll (meso=middle) 1. Palisade mesophyll -site of most photosynthesis 2. Spongy mesophyll -some photosynthesis

Leaves Stomata Guard Cells – Surround the stomata Gas exchange CO2 in – pores in the underside of the leaf Gas exchange CO2 in O2 out Guard Cells – Surround the stomata Open and closes stomata ***Stomata closed at night to prevent H2O loss

Transpiration Leaves Loss of water through its leaves Replaced by water drawn into the leaf

Transport in Leaves Xylem Phloem Vein (Vascular Tissue) “Water in” for photosynthesis Phloem “Glucose out” after photosynthesis

Tropisms Growing toward or away from a stimulus Phototropism Stimulus = Light Leaves have positive phototropism Thigmotropism Stimulus = Touch Vines have positive thigmotropism

Tropisms Growing toward or away from a stimulus Gravitropism Stimulus = Gravity Roots have positive gravitropism Hydrotropism Stimulus = Water Roots have positive hydrotropism

Plant Adaptations

Types of Adaptations Structural adaptations are the way something is built or made. Behavioral adaptations are the way something acts naturally or by instinct.

Behavioral Adaptations Adaptations to get food Plants like the Venus fly trap, trap insects for food.

Behavioral Adaptations Adaptations for reproduction Plants drop seeds to grow new offspring.

Structural Adaptations Adaptations to get water and nutrients Roots soak up water and nutrients from soil.

Structural Adaptations Adaptations for defense Spines and thorns protect plants from predators

Structural Adaptations Adaptations for defense Poison Ivy and Poison oak have toxins that give predators a painful itchy rash.

Desert Adaptations Small leaves or spines on desert plants conserve water. Thick waxy skin holds in water. Roots near the soils surface soak up rain water quickly before it evaporates.

Rainforest Adaptations Smooth, slippery bark keeps vines from killing trees. Slide shaped leaves lets rain run off so fungus doesn’t grow on plants.