Intro Plants

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Introduction to Plants

Navdeep K. Khehra


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Earliest Plants

Algae

Phytoplankton

Lived in the sea


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Problems with life on land

Problem

Drying Out Making Food

Reproduction

Gravity & Support

Getting water &

nutrients

Solution

Waxy cuticle, stomata Formed leaves

Develops spores &

seeds Bark (cork) & vessels

Roots & vessels


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Types of Plants

Avascular

Bryophytes

nonseed plants

Tracheophytesvessels for transport and

support


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Mosses & Liverworts: The

Bryophytes

First land plants

AVASCULAR = very small

500 m.y.a.

Must grow in moist environmentsUsed for fuel (peat)


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Reproduction in Bryophytes

Mosses have a protonema

(liverworts do not)Sexual reproduction

Antheridium makes sperm

Archaegonium makes eggsAsexual reproduction

Fragmentation

Formation of gemmae


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Tracheophytes

Vessels

XYLEM = transports water & dissolvedminerals from roots to leaves

PHLOEM = transports sugars from

leaves to rest of plant

Spores or seeds for reproduction


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Club Mosses (Lycophyta)

Leaves produce spores

Strobilus = spore-bearing leaves

Prothallus = produces antheridia &archaegonia


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Horsetails (Sphenophyta)

Jointed stems

Reproduction similar to club moss


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Ferns (Pterophyta)

400 m.y.a.

Dominant form = sporophyte

Structure

Rhizome = underground stem Fronds = leaves

Sori = store spores on underside of

fronds


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Gymnosperms

Gymno = naked Sperm = seed

First plants to produce seeds No flowers

No fruit


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Why Make Seeds?

Has own food supply

Protective coat against harshconditions

Some are designed for travel to new

areas


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Sporophytes produce:

MICROSPORE

Produce male gametophyte

Produce pollen

MEGASPORE

Produce female gametophyte

Produce ovule (makes archaegoniawith egg cells)


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Gymnosperm Reproduction

Pollen grains carried by wind

Land on ovule, develop pollen tube Sperm move through tube to fertilize egg

Fertilized egg = ZYGOTE

EMBRYO = young, diploid sporophyte plant COTYLEDONS = food storage for embryo,

become first leaves


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Why Pollen Instead of

Spores?

Plant can live in very dry areas

Fertilization does not require water

Pollen has protective coat and foodsupply for sperm


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Why Ovules Instead of

Archaegonia?

Protective tissues prevent drying out

Ovule holds archaegonia andprotects eggs from elements


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Minor Gymnosperm Groups

Cycadophyta (1st in Triassic Era)

Ginkgophyta Only one species today Ginkgo biloba

Most lived 200 m.y.a.

Gnetophyta only three genera Gnetum house plants

Ephedra weight loss, allergies & asthma

Welwitschia


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Coniferophyta (largest

group)

Needle or scale-like leaves

Bear seeds in woody cones Can live in very cold climates

Most are evergreens

Have wood

Made of thick-walled vessels (TRACHEIDS)

Tracheids are xylem


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Angiosperms

Angioflower Sperm seed

Extremely diverse

All have seeds enclosed in fruit


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Cambium

Any growth tissue in plants

Types of cambium Vascular = produces xylem & phloem

Cork = produces cork (bark)


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Overall Structures [121]

Roots

Stems

Leaves

Flowers


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Roots [124]

Absorb water & nutrients

Hold plant in place

Root types:

Fibrous

Tap

Prop

Aerial


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Stems [123]

Support leaves & flowers

Sometimes photosynthesis

Transport (contain xylem & phloem)

Types herbaceous green & flexible

Woody stiff, have cork layer, usually

brown


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Leaves [119]

Cuticle = protection

Stomata = gas exchange, water loss(transpiration)

Epidermis = protection, color

Mesophyll Palisade = most PHOTOSYNTHESIS

Spongy = Vascular bundles run through it


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Flowers [131]

Pistils = female reproductive structures

Stamens = male reproductive structures Complete flowers

Have petals & sepals

Have male and female parts

Incomplete flowers = missing one ormore parts


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Types of Angiosperms [115]

Monocots

mono = onecot = seed leaf

Approx. 60,000

species Flowers = multiples

of 3

Leaf veins parallel

Dicots

di = twocot = seed leaf

Approx. 170,000

species Flowers = multiples

of 4 or 5

Leaf veins branching


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Plant Tropisms

Tropism = plant response to external

stimulus Positive: plant moves toward stimulus Negative: plant moves away from stimulus

Types: Phototropism = light

Gravitropism = gravity

Thigmotropism = touch

(nastic movement direction does not matter)


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Plant Hormones

Hormone chemical produced in one

part of an organism that has an effect ona different part of the organism

Types Auxins regulate growth

Gibberellins speeds growth, germination

Abscisic acid dormancy, close stomata,stress

Ethylene ripens fruit

Intro Plants

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