Kingdom Plantae

Lower Plants, Organization, Morphology and

Reproduction

Plant Evolution

Ancestor = Charophytes member of the green algae

Problems associated with movement to land

1. Desiccation (dehydration)

2. Gas exchange

3. Support of multicellular structures

4. Reproduction

5. Spore or seed dispersal

Alternation of Generations

Alternation of generations

Diploid• Full # chromosomes• 2n• All non-gamete

cells• Can’t be gametes• Human = 46

• Haploid• ½ # chromosomes• n• Gametes• At fertilization

become diploid zygote

• Human = 23

Alternation of generations

Two Generations:

1. Sporophyte stage (spore-plant)a. Diploid stage (2n)

b. Produces haploid spores by meiosis

c. Spores grow into gametophyte containing male or female repro structures.

Alternation of Generations

Alternation of generations con’t.

Two Generations:

2. Gametophyte (n) (gamete plant)

a. haploid stage

b. Male: has antheridia, makes sperm

c. Female: has archegonia, makes eggs

d. gametes produced via MITOSIS

e. Sperm swim

f. Fertilization produces zygote

g. Grows into Sporophyte

Alternation of Generations

Bryophytes(nonvascular land plants)

Hepatophyta

Liverworts

Anthocerophyta

Hornworts

Bryophyta

Mosses

The Liverworts (Hepatophyta) - Marchantia sp.

Gemmae cups-asexual Female Gametophyte

Archegonia

The Hornworts (Anthocerophyta)

Anthoceros sp.

Moss plants – Bryophyta

gametophyte & sporophyte generations

See fig 27.12, Russell*

Adaptation to Land Problems associated with movement to land

1. Desiccation (dehydration)

2. Gas exchange

3. Support of multicellular structures

4. Reproduction

5. Spore or seed dispersal

Adaptation to Land (desiccation, gas xchge)

1. Stomata:

a. Openings in leaf surface

b. control H2O loss

b. allow for gas exchange

Adaptation to Land (desiccation,transport)

1. Stomata:

2. Vascular Structures

a. Xylem-H2O up from Roots

b. Phloem-sugar around

Adaptation to Land (dessication)

1. Stomata:

2. Vascular

3. Cuticle

a. H2O proof

b. prevents dessication

Cuticle(made of cutin)

Adaptation to Land (support)

1. Stomata: 2. Vascular Structures3. Support

a. Lignin in cell wallsb. allows for branching and larger size

BryophytesNo true roots or vascular tissue

- 2 cm tall

Still have a need for water (Repro)

Vascular PlantsDominant stage = sporophyte

(Gametophyte hidden)

Specialized organsa. Roots

- rhizomes

b. Stems

c. Leaves

Vascular plants con’t.

Branching

Some contain lignin

a. structural support

Vascular tissues

a. Xylem

b. phloem

Vascular Bundles inMonocot stem

Vascular plants con’t.Two types of growth – apical meristem

a. Primary growth

b. Secondary growth

Sperm still flagellated

Maintained stomata & cuticle

NonseedVascular

Plants

Lycophyta Psilotophyta Sphenophyta Pterophyta

Lycophyta Psilotophyta

Lycopodium sp. Psilotum sp.

(microphylls) (stems only)

Sphenophyta Pterophyta – the ferns

Equisetum sp.

Sori on the underside of sporophylls

Vascular Seed Plants

Coniferophyta- the gymnosperms

Anthophyta- the angiosperms

Seed plants

Purpose of the seed:

A. means of dispersal of offspring

B. Survive unfavorable conditions

C. Stores food for embryo

D. Protection from predatorsE. Remember “Seedy Side of Plants”

Seed plants (con’t.)

Non-flagellated sperma. pollen

b. Moved by water, wind, insects, and animals

c. Forms pollen tube for sperm

Egg cellsa. Called ovules located inside the

ovary

Seed plants con’t.

Reduced gametophyte

a. composed only of sperm or egg

Maintained:

a.vascular tissue,

b.Cuticle

c.stomata

Gymnosperms

A. Needle-like leaves

B. Found in moderately cold & dry regions

C. Direct pollination ovules NOT enclosed by tissue of the sporophyte (gym= naked)

Gymnosperm Life Cycle

Gymnosperms – naked seed plants

Cycads (Sego palm) Ginkgo biloba

Strobili: sporophylls (leaves with sporangia)

Phy: GinkophytaPhy: Cycadophyta

Welwitschia Ephedra

Phylum: Gnetophyta

Coniferophyta

Angiosperms

1. Produce flowers, seeds and fruit

2. Petals brightly colored to attract pollinators

3. Dominate the landscape

The anatomy of a flower

Flower anatomy con’t.

Angiosperms con’t.

Pollination1. Pollen grain lands on stigma and

germinates2. Pollen tube grows down through

style into ovary releases sperm into ovules (egg cells)

3. Mature ovary = fruit4. Mature ovule = seed

Pollination

Monocots vs. Dicots

Mono Dicot

1. 1 cotyledon 2 cotyledons

2. Parallel vein net-like vein

3. Fibrous root tap root

4. Flwr parts in 3 flwr parts in 4-5

5. Scattered bundles bundles in ring(in the stem)