plant organs
TRANSCRIPT
Plant Organs Organs: tissues that act together to serve a specific function.
DermalVascularGround
DermalVascularGround
DermalVascularGround
Stems
Roots
Leaves
Plant Organs
Plant Organs – Organs composed of
one or more tissues.– Three major types:
• Roots• Stems• leaves
– Flowers and fruits evolved from stems and leaves
Function of Plant Organs
ROOTS – Function Anchorage Absorption Storage Conduction
STEMS –Function Suppor Transport.
LEAVES – Function Photosynthesis
ROOTS “the hidden half” Functions of roots:
Anchorage Absorption of water &
dissolved minerals Storage (surplus sugars,
starch) Conduction water/nutrients
ROOT
Structure of RootsLongitudinal section of roots Root cap
Zone of cell division Zone of cell elongation Zone of maturation
Cross section of root Vascular bundle (Stele)
contains xylem and phloem Cortex Epidermis Root hairs
Absorb water and minerals
Types of Roots– Fibrous, multibranched roots (e.g. lettuce)
– Dominant tap root
– Adventitious roots• root-like structures arising from stems or leaves• e.g. prop roots (corn) and holdfasts
– Tuberous roots • Swollen structure on fibrous root used to store
carbohydrates (e.g. sweet potato)
• Tap roots used to absorb water deep in soil• Some tap roots used to store carbohydrates (e.g. carrots)
Fibrous roots Tap root
Adventitious roots Tuberous roots
Types of Roots
STEMS Above-ground organs.
(usually)
Support leaves and fruits.
Conduct water and sugars throughout plant.
STEM STRUCTURES
Nodes: location of leaves on stem Internodes: stem between leaves Buds: undeveloped leaves or flowers
– Terminal (apical)– axillary (lateral)– Apical dominance is growth inhibition caused by
apical bud
Stem Structure
Function of Stems Support leaves, flowers, fruits. Transport of water (xylem) and
products of photosynthesis (phloem). Storage of carbohydrates
Tubers - swollen underground stems that store carbohydrates (e.g. potato).
Corm - swollen base of stem covered in papery leaves. Bulb - cluster of fleshy leaves attached to short, thick stem with basal roots (e.g. onion).
Bulbils - tiny bulbs arising in leaf axils. Rhizome - horizontal stem below ground
that produces roots and shoots at each node.
Stems Stems used only for asexual reproduction. Stolon (or runner) - horizontal stem that arises
from leaf axel and runs above ground (e.g. spider plant) When tip of solon hits ground a new plant
forms
Spur - stem with short internodes growing from a larger branch of woody plant.
Waterspout - stem that arises from latent buds in branches of woody plants.
Sucker - stem arising from root tissue, often from cut woody plant.
Types of modified stems
Types of Stems
Tendrils - twining stems used to secure climbing plants to vertical surfaces (e.g. peas, grapes).
Prickles - tiny, pointed projections of epidermis tissues of stems (e.g. blackberry).
Thorns - long, pointed projections produced in leaf axils (e.g. Hawthorn).
Cladophylls - stems modified for photosynthesis (e.g. cacti, asparagus).
Types of Stems Types of modified stems
Types of modified stems
Types of modified stems
LEAVES
Most leaves are thin and flat An adaptation that helps them capture sunlight for
photosynthesis. Although this structure may be typical, it is certainly
not universal. Leaves are extremely variable. This variability represents adaptations to
environmental conditions.
Blade - Flat expanded area
Petiole - stalk that connects leaf blade to stem, and transports materials
Pair of stipules
Leaf parts
Leaves structure
Leaf epidermis Is transparent – so that sun light can go through. Waxy cuticle protects against drying out Lower epidermis: stomata with guard cells – for gas
exchange (CO2, H2O in; O2 out)
A. CuticleB. Upper epidermisC. Palisade layer D. Spongy LayerE. Lower epidermis
Leaves functions
Leaves
Carry out photosynthesis in order to make glucose.
Composed of epidermal, vascular and ground tissue.
Flower A flower is the reproductive organ of angiosperms. Flowering plants reproduce by pollination.
Flower To Fruit
A fruit is defined as a ripened ovary that contains angiosperm seeds.
The function of a fruit is to hold and protect the seeds.
Fruits
Each kernel of corn on a cob is actually an individual fruit
In peaches, the fruits are soft and fleshy and contain a single, stony seed.
Legumes like beans and peas produce a fruit called a pod that contains many seeds.
The End
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