Plant Structures Roots Stems and Leaves Chapter 23

Plant Structures Roots, Stems, and Leaves Chapter 23

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

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

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

Functions of Leaves n n Main photosynthetic systems Sight of gas exchange

Tissues in Plants 1. 2. 3. Dermal tissue Vascular tissue Ground tissue

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

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

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

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

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

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

Stems n 2 types of stems 1. 2. Herbaceous Woody

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

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

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

Leaves n Stomata n n n – pores in the underside of the leaf Gas exchange n CO 2 in n O 2 out Guard Cells – Surround the stomata n Open and closes stomata ***Stomata closed at night to prevent H 2 O loss

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

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

Tropisms Growing toward or away from a stimulus Phototropism Stimulus = Light Thigmotropism Stimulus = Touch Leaves have positive phototropism 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 n n Structural adaptations are the way something is built or made. Behavioral adaptations are the way something acts naturally or by instinct.

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

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

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

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

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

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

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