Transcript Botany-2016x - Fluvanna Master Gardeners

BOTANY
The Study of Plants
Where Do Plants Fit In
• Domains:
– Bacteria: most prokaryotes (no nucleus or
intracellular organelle)
– Archaea: have many biochemical differences from
bacteria and often live in extreme environments
– Eukaryotes (true nucleus):
• Fungi
• Plantae
• Animalia
Plant Classification
• Non-vascular Plants - lack tissues to transport
water and sap:
• Green algae
• liverworts
• Mosses
– Leaves are a single layer of cells
Vascular Plants
Tube like structures distribute water, nutrients
and food throughout the plant.
Ferns – Spores, (no seeds)
Gymnosperms – “Naked” seeds (mostly conifers)
Angiosperms – Flowers and seeds
Gymnosperm - Pine
Angiosperms
Monocotyledons – One seed leaf
grasses, lilies, palms, yuccas, agaves
Reproductive parts in threes or multiple of three
Three petals etc
Dicotyledons –Two or more seed leaves
Most deciduous trees & herbaceous plants
Reproductive parts in fours or fives: four or five petals
Monocots and Dicots
A practical note: Some herbicides act
differently on dicots vs monocots.
Scientific names
• Based on classification
• In angiosperms based on flower
structure
• Uniformity among texts and discussions
• Often tell us something about the plant
PLANT CLASSIFICATION
• Kingdom: Plantae
• Division: Tracheophyta (vascular)
• Class: Angiospermae (seeds in fruits)
• Order: Campanulatae
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Family: Asteraceae (Compositae)
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Genus: Coreopsis
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Species: lanceolata (lance-shaped)
Vascular Plants-further classification
Annuals: Complete a life cycle in one year.
Most vegetables, grains, some ornamental plants.
Plant may germinate in fall, live through the winter and die after making
seeds the next year. Example: Poppies
(An “annual” in our zone may be able to live more than one year if grown in
tropics.)
Biennials complete a life cycle in two years.
Perennials live longer than one year.
Herbaceous perennials die back to regrow the following growing season.
Many ornamental garden plants. Asparagus.
Woody perennials, either deciduous or evergreen, do not die back.
Vascular Plants
• Plants with:
– Roots
– Stems
– Leaves
– Vascular systems: extend from root tips up the
stems and out into the leaves.
ROOTS
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Have no nodes
Never bear leaves or flowers directly
Have a root cap
Function: absorb water and nutrients
– Anchor the plant
– Furnish physical support for the stem
– Serve a food storage
Root Cap
• Not present in
“water roots”
ROOTS
Root growth in loose vs compact
soil
Specialized Roots
• Tap root: large main root taps deep for water,
develops from radicle and produces lateral roots
• Fibrous root (a form of adventious root) common
in monocots and seedless plants
• Adventious root: not from radicle
• Aerial root arises from stem (ivy, orchid)
• Buttress root (Ficus)
• Suckers
• Pneumatophores provide oxygen in wet
areas
Mycorrhizae
• From mykes or fungus and rhiza or root
• Symbiotic relationships between fungi and
plant roots: the fungi get sugars or food
and the plants absorption of water and
minerals is greatly enhanced
• Occurs in >80% of vascular plants
Mycorrhizae
Specialized Roots
• Tap root: large main root taps deep for water,
develops from radicle and produces lateral roots
• Fibrous root (a form of adventious root) common
in monocots and seedless plants
• Adventious root: not from radicle
• Aerial root arises from stem (ivy, orchid)
• Buttress root (Ficus)
• Suckers
• Pneumatophores provide oxygen in wet
areas
Plant Stems
• Support the weight of leaves
• Conduct water and minerals up to leaves
and food down to roots in the vascular
tissue
• Complex growth: produces leaves and
branches at nodes as well as lengthens
Plant Stem
Stem or Twig
Vascular Cambium
• Produces phloem peripherally which
transports sap to the roots and back from
the roots in early spring or late winter
• Produces xylem internally which transports
water
• If completely interrupted, the plant will die
Meristem or Cambium
• Site of cell division and growth located
between phloem and xylem. If this is destroyed
the stem cannot form new cells for transport of water and
sap.
• At nodes and at the tip meristem tissue
forms buds.
– Flower parts are modified leaves
Stem Cross Section
Woody Stem Cross Section
Apical Meristem
Plant Stem Tip
Specialized stems
• Rhizome: horizontal underground stem with
(nodes and buds); iris, bermudagrass
• Bulbs: shortened, compressed stem surrounded
by leaves (scales) that envelop a flower bud
• Corm: similar to bulb with scales reduced to dry
covering
• Tuber: enlarged portion of underground stem;
potato with nodes as “eyes”
Rhizome
• The iris has a large fleshy underground
stem that runs parallel with the soil.
Leaves
• Site of photosynthesis. Plants are
photoautotrophs: they use light to make their
own organic compounds and oxygen.
• Light is the energy source and CO2 is the
carbon source.
• Plants also respire but the net effect is the
production of oxygen in excess of carbon
dioxide.
Leaf Structure
• 1. Cutin, 4. Spongy parenchyma
• 2. Epidermis 5. Air space
• 3. Palisade layer 6. Stoma
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Leaf Arrangement
• Simple. Opposite, alternate, whorled
• Compound: Leaflets Palmate, Pinnate or
Double Pinnate
• **Leaves attach to stems at nodes and
buds occur only at nodes.
• (a common error is to mistake a leaflet for
a leaf)
Simple leaves
Leaf arrangement
Compound Leaves
Sexual Reproduction
Occurs in all plants. Involves meiosis or halving
the number of chromosomes so that sperm and
ova are produced. These then unite to produce
a new combination of chromosomes and genes.
Gymnosperm
Flower Structure
Gymno vs Angiosperm
Pollination and Fertilization
Pollination: Pollen is carried by wind, insect,
bird, water….from the anther to a stigma.
Fertilization: The sperm cell unites with the egg
cell in the ovule.
SEEDS
• Develop from ovule
• Cotyledon--seed leaf
• Radicle--first root
Seed Germination
• Period of dormancy
• Factors: scarification, stored food
– Temperature: some require a period of cold
– Moisture
– Light
– Oxygen (water logged soil may prevent
germination)
Seed Dispersal
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Plumes: butterfly weed, dandilions, maples
Fruit: acorns, hollies, apples
Water: coconuts
Spines and barbs: beggar’s tick
Explosive fruits: jewel weed
Hybrid
• Hybrid: a plant or animal which is the
offspring of parents differing in one or
more characteristics. The parents may be
of the same or different species.
• Species:a group of individuals if nearly
identical structure and behavior which can
ordinarily interbreed and maintain their
characteristic in nature.
Red crossed with white produces pink
(hybrid) flowers
Genetic variability
• In a given species or variety a gene may have
quite a variable expression.
• Example: apple trees have so much variability
that to propagate a standard one must use
grafted stock. If one uses seeds the two parent
trees contribute such different characteristics
that one usually gets something very different
from either parent.
Gene Dominance
• If S is dominant over s when SS is mated to ss
all of the offspring will appear S. The offspring
will be Ss.
(The Ss is the hybrid.) If Ss is mated to Ss, the
offspring will be SS, Ss or ss and the ss will
appear different.
If there are multiple genes acting in such a way the
offspring of the hybrids may have many
differences from the hybrids.
Genetic variability
• In a given species or variety a gene may have
quite a variable expression.
• Example: apple trees have so much variability
that to propagate a standard one must use
grafted stock. If one uses seeds the two parent
trees contribute such different characteristics
that one usually gets something very different
from either parent.
Gene Dominance
• If S is dominant over s when SS is mated to ss
all of the offspring will appear S. The offspring
will be Ss.
(The Ss is the hybrid.) If Ss is mated to Ss, the
offspring will be SS, Ss or ss and the ss will
appear different.
If there are multiple genes acting in such a way the
offspring of the hybrids may have many
differences from the hybrids.
Propagation from Seeds
• The offspring may vary from the parents
because of genetic variability or if the
parent was a hybrid.
• This may be desired in some cases, but in
apples usually the offspring are not tasty.
PLANTS: Bryophytes
• Bryophytes (moss-plants) non-vascular,
seedless: Mosses: sphagnum, rock
mosses, “true mosses, Liverworts,
Hornworts
Cell walls of cellulose
Do not produce flowers
MOSS
• MOSS
Moss Cultivation
• Mosses need moisture to complete their
life cycle. Many can survive dry periods
but the spores need water.
• Generally does well in shade, often grows
on rocks.
• Grows in wide range of pH.
• Plant other garden plants first then add the
moss
LIVERWORT
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Seedless Vascular Plants
• Lycophyta: club mosses, selaginellas,
quillworts
• Sphenophyta: horsetails
• Pterophyta: ferns
Clubmoss
• Lycopodium
Selaginella
Selaginella
Equisetum (Horsetail)
Equisetum
Ferns
• Need moisture to complete the life cycle
but often grow in a variety of conditions
Life Cycle of Fern
Ferns
• Maidenhair
Non-flowering Plants
• Can be interesting as well as beautiful
additions to outdoor and indoor gardens.
• They often need high humidity and some
shade
– The north side of the house is often a good
habitat for selaginellas and ferns
Adaptations of Plants
• Drought tolerance
– Succulents have large vacuoles to store water
– Waxy coats to avoid water loss
– Small leaves or needles to decrease surface
area (less effect from wind)
– Stomata close during the day (cacti)
– Hairs on leaves to collect moisture
Seed Dispersal
• Plumes: butterfly weed, dandilions, maples
• Fruit: acorns, hollies, apples
• Water: coconuts
• Spines and barbs: beggar’s tick
• Explosive fruits: jewel weed
Galls
Oak Leaf Gall
Urchin Gall
Monarch on Milkweed
• Monarchs prefer more than one species of
milkweed