Kingdom Plantae

Plant Morphology

Plant Evolution

Ancestor = Charophytes member of the green algae

Evidence that supports this idea:

1. Homologous chloroplastsSimilarity in characteristics d/t common

ancestry

2. Biochemical similarity

3. Similarities in cytokinesis

4. Sperm cell ultrastructure

5. Genetic relationships

Problems associated with movement to land

1. Desiccation

2. Gas exchange

3. Support of multicellular structures

4. Spore or seed dispersal

5. Reproduction

Alternation of generations

Two Generations:

1. Sporophyte stagea. Diploid stage

b. Sporo = spore (n) planta. sporopollenin

c. Spores produced via meiosis

d. Sporangium sporocytes (2n)

Alternation of generations con’t.

Two Generations:

2. Gametophyte

a. haploid stage

b. gameto = gamete plant

c. gametes produced via MITOSIS

Monocots

Dicots

Angiosperms ovary

Gymnosperms no ovary

seeds

Cryptogams spores

vascular

Bryophytes nonvascular

land

Sporophyte dominates life cycle

Bryophytes(nonvascular land plants)

Hepatophyta

Liverworts

Anthoceros

Hornworts

Bryophyta

Mosses

Bryophytes

Gametangia = structures where gametes are produced

a. Archegonia - egg cells

b. Antheridia – sperm cells

* Sporophyte cannot live independently

Moss plants – gametophyte & sporophyte generations

The Liverworts (Hepatophyta) - Marchantia sp.

The Hornworts (Anthocerophyta)

Anthoceros sp.

Bryophytes con’t

Stomata

a. openings in leaves that allow for gas exchange

Bryophytes con’t

Cuticle

(made of cutin)

Bryophytes con’t.

No fundamental difference between above and below ground parts

- 2 cm tall

Still have a need for water

Vascular Plants - TracheophytesDominant stage = sporophyteSpecialized organs

a. Stemsb. Leaves

- megaphyll- microphyll

c. Sporophylls: specialized leaf to house meiosporangia

- Many cone shaped- Homosporous & heterosporous

d. Roots- rhizomes

Vascular plants con’t.

Branching increased sporangia

Some contain lignin

a. structural support

Vascular tissues

a. Xylem

b. phloem

Vascular plants con’t.

Two types of growth – apical meristem

a. Primary growth

b. Secondary growth

Sperm still flagellated

Maintained stomata & cuticle

Vascular Plants - Tracheophytes

plants w/ pipes

Broken up into two groups:

1. Reproduce by sporesCryptogams: crypto: hidden, gam: sex

2. Reproduce by seeds

Gymnosperms: naked seed plants (cones)

Angiosperms: seed surrounded by ovary (flowers)

Tracheophytes- Cryptogams

Lycophyta Psilotophyta Sphenophyta Pterophyta

Innovations of the Cryptogams

1. Roots- uptake water, minerals, nutrients, and gases

2. Vascular tissue- xylem & phloem arranged in bundles

3. Division of labor- specialized tissues and organs

4. Lignin- infused in xylem support against gravity

5. Hormones- regulate plant development

P: Lycophyta

C: Lycopodiopsida

(microphylls)

P: Lycophyta

C: Sellaginellopsida

Sellaginella – The resurrection plant

l.s. strobilus

P: Psilotophyta

* stems only

P: Sphenophyta

Equisetum sp. - Horsetail Aerial stem in c.s.

Equisetum gametophyte & sporophyte stages.

Equisteum strobilus (cone: compact group of meiosporangium-bearing structures). Left: whole mount and Right: cross section showing sporangiophore: stem-like structure bearing sporangium (container in which spores are borne).

P: Pterophyta – the ferns Gametophytes

Sori (cluster of meiosporangia) on the underside of sporophylls (specialized leaf that bears meiosporangia) aka fronds.

Sori in c.s.

Note – indusium: layer of tissue protecting meiosporangia filled with meiospores. Annulus (head portion of meiosporangia) also present.

Left: fern gametophyte (prothallium) with archegonia and antheridia. Right: sporophyte growing out of gametophyte. Rhizoids present.

Vascular Seed Plants

• Gymnosperms – naked seed plants

• Angiosperms – flowering plants

Seed plant characteristics

• Seeds

• Reduced gametophytes – microscopic

- Gametophytes develop from spores retained in sporangia of parental sporophyte protects female gametophyte from environmental stresses

- Gametophyte obtains nutrients from sporophytes

Seed plant characteristics con’t.

• Heterospory– Megasporangia: produce megaspores that give

rise to female gametophytes• egg within ovule

– Microsporangia: produce microspores that give rise to male gametophytes

• sperm within pollen

Seed plants con’t.• Non-flagellated sperm

a. pollen

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

• Egg cellsa. Called ovules located inside the

ovary

Seed plants

• Purpose of the seed:

A. means of dispersal

B. Survive unfavorable conditions

C. Stores food for embryo

D. Protection from predators

Seed plants con’t.

• Characteristics Maintained:

-vascular tissue

-cuticles

-stomata

Gymnosperms

Cycadophyta Ginkgophyta Gnetophyta Coniferophyta

Gymnosperms

• Needle-like leaves

• Found in moderately cold & dry regions

• Direct pollination ovules NOT enclosed in ovaries

i. dioecious: seeds & pollen produced on different sporophytes

ii. strobili: micro and megasporophylls

P: Cycadophyta

Phylum: Ginkgophyta

Ginkgo biloba – single species in the phylum.

i. dioecious

ii. male pollen cone w/ 2 microsporangia (whole & l.s.)

iii. no seed cone ovules on end of branches

Phylum: Gnetophyta

Welwitschia – found in the deserts of Africa

i. dioecious

Phylum: Gnetophyta con’t.

Ephedra

pollen cone: note microsporangia (compound strobilus)

seed cone: will produce two seeds

Phylum:Coniferophyta

Conifer characteristics

• largest group of gymnosperms (600 spp.)

• most are evergreen, monoecious, trees or shrubs

• needle or scale-like leaves

• compound seed cones (ovules on cone scales)

• Simple or clustered pollen cone

Needle-like leaves

-Curled bracts

- fasicle (group of needle-like leaves attached to a single shoot) bundled in a papery sheath

Angiosperms

1. Produce seeds and flowers

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)