botany 101b
DESCRIPTION
Master Gardener botany presentationTRANSCRIPT
Warren County Master Gardener Class
Botany 101
Carol La Faver
CEA for Horticulture—Warren County
When Is a Tree a Tree?
Tree
A woody perennial plant having a single usually elongate stem generally with few or no branches on its lower part.
Shrub
A low usually several stemmed woody plant.
Herb A seed-producing,
biennial, or perennial that does not develop persistent woody tissue but dies down at the end of a growing season.
Plants Have Two Parts Sexual
Flower Buds
Flowers
Fruit
Seeds
VegetativeLeaves
Leaf Buds
Roots
Stems
Stems
Structures which support buds and leaves and serves as conduits for carrying water, minerals and sugars
Three Major Internal Parts of Stems
Xylem – conduct water and minerals
Phloem – conduct sugars
Cambium – a meristem, the site of cell division and active growth, located between the xylem and phloem
Table 1. Comparison between monocots and dicots.
Structure Monocot Dicot
Seed leaves 1 2
Vascular system
Xylem and phloem are paired in bundles, which are dispersed throughout the stem.
Xylem and phloem inside the stem. The ring of phloem is near the bark; the xylem forms the inner ring.
Floral parts Usually in multiples of three.
Usually in multiples of four or five.
Leaves Often parallel-veined.
Usually net-veined
Cross-section of Stems
Pith
Node and Internode A node is the area of
stem where leaves are located.
An internode is the area of a stem between the nodes.
Modified Stems Crown – compressed stem tissue Runner – stem that grows on the soil
surface What is an example of a plant that has both
of these “stems”? Strawberry
Modified Stems (cont.) Spurs – Short stubby
side stems. Stolon – aboveground
horizontal stem Tuber – the eyes are
the nodes of the “stem”
Modified Stems (cont.) Rhizomes –
Underground horizontal stem, i.e. iris, johnsongrass.
Bulbs – Compressed underground stems surrounded by fleshy leaves, i.e. tulips, daffodils,lilies, and onions.
Modified Stems (cont.) Corms – Similar to
bulbs but do not have fleshy scales
Tuberous Stems – shortened, flattened, enlarged and underground, i.e. tuberous begonia
Tuberous Root Not a stem but an
underground storage organ
Stems have nodes but roots do not.
Stem Terminology -
Shoot - A young stem (1 year old or less) with leaves.
Twig - A young stem (1 year old or less) that is in the dormant winter stage (has no leaves).
Branch - A stem that is more than 1 year old, typically with lateral stems radiating from it.
Trunk - A woody plant's main stem.
Vines
Attach by Twining Morning glory
Vines
Attach by Aerial Roots Poison Ivy
Vines
Attach by tendrils Some wrap around and some with adhesive pads Virginia Creeper
Leaf Scar
Lenticels
Thorns
Parts of a Leaf
Blade Midrib Vein Petiole
Leaf Facts Principle function of leaves is to absorb
sunlight for photosynthesis What are leaves flat? (except conifers) Petiole is attached to the stem at a node Angle between the petiole and the stem is
the leaf axil Buds are located in the leaf axil
Leaf Facts (cont.) Epidermis –
thickened layer on top & bottom of leaf
Primary function is leaf protection
Some epidermis cells have hairs
Leaf Facts (cont.) Cuticle has a waxy
substance called cutin Protects the leaf from
dehydration and disease The amount of cutin is
direct response to sunlight
What does this have to do with hardening a plant off?
Leaf Facts (cont.) Guard cells on the
underside of leaf can open and close
The opening is a stoma
Allows for the passage of water, oxygen, and carbon dioxide
Leaf Facts (cont.) Weather determines
the opening and closing of the guard cells
Guard cells will close during darkness
Leaf Types Cotyledons or seed
leaves Spines Scale leaves Tendrils succulent storage
leaves Bracts -- Dogwood
Leaf Venation – Parallel, Pinnate, and Palmate
Shapes of Leaves – Simple, Palmate Compound, Pinnate Compound, & Double Pinnate Compound
Shape of Leaf Blade – Oblong, Lanceolate, Linear, Ovate, Elliptical, Orbicular, Cordate
Shape of Leaf Base - Hastate,
Sagittate, Peltate, Perfoliate,Terete
Leaf Margin – Entire, Serrate, Serrulate, Dentate, Undulate, Crisped, Pinnatifid
Leaf Arrangement on Stem
Alternate
Opposite
Whorled
A Bud Is an Undeveloped Shoot Leaf bud – short stem
with embryonic leaves, less plump and more pointed than flower buds
Flower bud – a short stem with embryonic flower parts
Types of Buds Terminal bud - at end
of stem Lateral bud - on the
sides of stem Axillary bud - in axis
of leaf Adventitious bud –
i.e. on root or edge of leaf
Roots Originate from lower
part of plant or cutting
Have a root cap, no nodes, and never have leaves or flowers
Principle Functions of Roots Absorb nutrients and moisture Anchor the plant in the soil Furnish physical support of the stem Serve as food storage organs May be used as a means of propagation
Types of Roots Primary (radicle) root
from embryo Taproot Lateral or secondary
root Fibrous root
Parts of a Root Meristem- area of cell
division and growth Zone of elongation –
cells increase in size, push root through soil
Maturation zone – become specific tissue, i.e. epidermis, vascular tissue
Parts of a Root
Root hairs – water & nutrient absorption
Root cap – covers and protects the meristem
What Does This Picture Tell You?
Parts of a Flower Sepals – leaf-like
structures at base of flower for protection
Petals – highly colored often fragrant
Petals are often used for ID of plant family
Nectar glands
Parts of a Flower (cont.) Stamen – male
reproductive organ consisting of anther and filament
Pistil – female part of the plant. It consists of stigma, style, ovary, ovules and eggs
Types of Flowers Complete flower –
has stamen, pistils, petals, and sepals
Incomplete flower- has one of these parts missing
Types of Flowers Perfect flower – has
functional stamens & pistils
Imperfect flower – if either pistil or stamen is missing
Types of Flowers Pistillate or female
flowers have no stamen
Staminate or male flowers have no pistils
Types of Plants Dioecious – has only
a male or a female flower – Holly, gingko
Monecious – plant has both separate male and female flowers - corn
Inflorescence – Spike, Panicle, Raceme, Head, Umbel
Pollination & Fertilization
Types of Fruit Simple – develop from a single ovary
Aggregate – develop from a single flower which has many ovaries
Multiple – tight cluster of individual flowers borne on a single cluster
Parts of a Seed (a Mature Ovule) Embryo – a miniature
plant in an arrested state of development
Endosperm – built in food supply
Seed Coat – hard outer covering to protect seed
Germination The resumption of
active embryo growth Radicle (root)
emerges first Hypocotyl – area
between the first leaves and root (stem)
Seed leaves encase the embryo
The Three Major Plant Functions
Photosynthesis – food production
Respiration – uses food for plant energy
Transpiration – process for moving/losing water
Photosynthesis
Carbon dioxide + Water + Sunlight = Sugar + Oxygenor
6 CO2 + 6 H20 + Energy => C6H1206 + 6 02
Photosynthesis Occurs in Chloroplasts
Factors Affecting Photosynthesis Light availability – increases as light
increases Carbon dioxide – carbon & oxygen are
used to make carbohydrates Temperature – photosynthesis highest in
the range of 65 to 85 degrees F, decreases when above and below
Factors Affecting Photosynthesis
Water – split by the sun’s energy into hydrogen and oxygen, oxygen released while hydrogen is used to make carbohydrates
Respiration
C6H12O6 + 6 O2 => 6 CO2 + 6 H2O + Energy
Table 2. Photosynthesis and Respiration.
Photosynthesis Respiration
•produces food •stores energy •uses water •uses carbon dioxide •releases oxygen •occurs in sunlight
•uses food •releases energy •produces water •produces carbon dioxide •uses oxygen •occurs in the dark as well as light
Transpiration is responsible for:
•Transporting minerals from the soil throughout the plant. •Cooling the plant through evaporation. •Moving sugars and plant chemicals. •Maintaining turgor pressure.
Photosynthesis, Respiration and Transpiration Work Together
Environmental Factors That Affect Plant Growth
Light
Temperature
Water
Light Quantity – concentration of sunlight, varies with
season. How can you decrease it? Quality – color reaching the plant. Red & blue
have greatest effect on growth, green is reflected.
Blue light = leaf growth; Blue light + red light = flowering.
What light do you want for seedlings?
Light (cont.) Duration – Amount of time a plant is
exposed to light.
Plants flower in response to uninterrupted dark periods.
Plants are classified as either Short-day or long-day or Day-neutral.
Light (cont.) Short-day plants – form flowers when day
length is less than 12 hours in duration. Mums & Pointsettia
Long-day plants – form flowers when day length exceed 12 hours. Lettuce & Rudbekia
Day-neutral plants – form flowers regardless of day length. Petunia
Temperature If temperature is high and day length long
cool season crops will bolt. If temperatures are too low then warm
season crops may not set fruit. Adverse temperatures will cause stunted
growth and poor quality, i.e. bitter lettuce in high temperature.
Temperature Effects on Plant Growth
Photosynthesis – increase with temp to a point
Respiration – rapidly increase with temp Transpiration – increase with temp Flowering – partially triggered by temp Sugar storage – low temp reduce energy
use increase sugar storage Dormancy – warmth will break dormancy
Water
Maintains turgor pressure which regulates the opening and closing of the stoma.
Stoma are involved in the gradual evaporation of water from the leaf surface which help stabilize the plant temperature.
Relative Humidity
The water in the air divided by the amount of water the air can hold (at constant temperature and pressure).
Relative Humidity Warm air can hold more water so if water amount
remains the same and temps go up then relative humidity goes down.
Water vapor will move from an area of high humidity to one of low humidity.
Humidity inside a leaf is close to 100% When stoma opens the water vapor rushes out
causing the humidity on leaf surface to go up.
Relative Humidity (Cont.)
The “cloud” of humidity slows down transpiration and cools the leaf.
What happens to transpiration if the wind starts to blow?
Nutrients Essential for Plant GrowthAir/water Macronutrients Micronutrients
Carbon (C) Nitrogen (N) Iron (Fe)
Hydrogen (H) Potassium (P) Zinc (Zn)
Oxygen (O) Phosphorus (K) Molybdenum (Mo)
Magnesium (Mg) Manganese (Mn)
Calcium (Ca) Boron (B)
Sulfur (S) Copper (Cu)
Cobalt (Co)
Chlorine (Cl)