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L13: Bryophytes

BIOL 153/LBlack Hills State Univ.Ramseys

I. Delineation of groups by phylogenyA. Definitions

1. Monophyletic group

all descendents of one common ancestor

2. Paraphyletic group

many but not all descendents of one common ancestor

3. Polyphyletic group

descendants of two (or more) ancestors

I. Delineation of groups by phylogenyB. Illustrations using trees

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Fig. 12-4Raven p. 238

Fig. 12-4Raven p. 238

I. Delineation of groups by phylogeny

C. Treatment of non-monophyletic groups

1. Functional groupings

paraphyletic or polyphyletic groups of organisms with similar ecology

Examples:

• "Algae"

• "Moss"

• Phytoplankton

2. Paraphyletic groupings (almost monophyletic)

otherwise monophyletic group in which one lineage is elevated

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Example: II. Origin of Land Plants

A. Green Plants

Photosynthetic Organismson the Tree of Life

Primary Origin of Chloroplast

Primary Origin of ChloroplastPlant Kingdom(Green Plants)

II. Origin of Land Plants

B. Land Plants

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1. "Bryophytes"

mosses, liverworts, hornworts

2. "Ferns & Fern Allies"

ferns, lycopods, horsetails, spike moss

3. Gymnosperms

conifers, cycads, ginkgo, gnetophytes

4. Angiosperms

flowering plants (dicots, monocots)

II. Origin of Land Plants

C. Paraphyly in Green Plants "Green Algae"

"Bryophytes"

"Ferns & Allies"

Red Algae

Gymnosperms & Angionsperms

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"Green Algae"

"Bryophytes"

Red Algae

Gymnosperms & Angionsperms

"Ferns & Allies"

"Green Algae"

"Bryophytes"

Red Algae

Gymnosperms & Angionsperms

"Ferns & Allies"

"Ferns & Allies"

"Green Algae"

"Bryophytes"

Red Algae

Gymnosperms & Angionsperms

"Green Algae"

"Bryophytes"

"Ferns & Fern Allies"

Red Algae

Gymnosperms & Angionsperms

Plant Kingdom

aka

Green Plants

Two-kingdom system

Three-kingdom system

Five-kingdom system

Modern system

"Green Algae"

"Bryophytes"

"Ferns & Fern Allies"

Red Algae

Gymnosperms & Angionsperms

LandPlants

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III. Life on Land

A. Challenges

1. Dessication

loss of moisture to environment

2. Gamete movement

aquatic organisms have swimming gametes

3. Structural support

tissues of aquatic organisms bouyantand flexible

4. Transport

large dessicant-resistant body has transport + exchange challenges!

5. Atmospheric oxygen

O2 bad for plants (inhibits photosynthesis)

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III. Life on land

B. Adaptations in Green Plants

1. Embryo

multicellular embryo is protected, given head-start

2. Stomata

small pores for gas exchange

3. Vascular tissues

xylem + phloem for water + sugar

4. Wood

structural tissue (stems, roots)

5. Pollen

small protected male gametophyte (transports sperm)

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6. Seeds

protective case w/ food for embryo

"Green Algae"

"Bryophytes"

"Ferns & Fern Allies"

Red Algae

Gymnosperms & Angionspermsorigin of terrestrial

adaptations in Green Plants

"Green Algae"

"Bryophytes"

"Ferns & Fern Allies"

Red Algae

Gymnosperms & Angionsperms

Stomata

Embryo

"Green Algae"

"Bryophytes"

"Ferns & Fern Allies"

Red Algae

Gymnosperms & AngionspermsVascular tissues

"Green Algae"

"Bryophytes"

"Ferns & Fern Allies"

Red Algae

Gymnosperms & Angionsperms

Wood Pollen Seeds

IV. Introduction to "Bryophytes"

A. Types

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1. Mosses

small, mat-forming; elongate gametophyte w/ simple leaves; threadlike sporophyte

widespread and diverse

2. Liverwort

flattened thallus, leafless; stalk-like sporophyte w/ umbrella head

widespread and diverse

3. Hornworts

ribbonlike thallus, leafless; horn-shaped sporophyte

mostly tropical, not many species

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IV. Introduction to "Bryophytes"

B. Evolutionary relationshipsHornwortsLiverworts

Mosses

IV. Introduction to "Bryophytes"

C. Dominance of gametophyte stage

largest, most persistent stage is gametophyte

IV. Introduction to "Bryophytes"

D. Life in terrestrial environment

1. Adaptations present

embryo + stomata

Fig. 16-8Raven p. 371

sporophyte developing fromembryo (liverwort)

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Fig. 16-25Raven p. 384

Stomata(moss)

1. Adaptations present

2. Adaptations absent

embryo + stomata

vascular tissue + roots wood, pollen, seedsflowers + fruits

V. Life cycles of "Bryophytes"

A. Key concepts

1. Spore vs. gamete

spores are direct product of meiosis, do mitosisgametes produced later, undergo fertilization

2. Sporophyte vs. gametophyte

sporophyte is diploid, produces spores by meiosisgametophyte is haploid, produces gametes by mitosis

3. Archegonia and antheridia

multicellular structures on gametophyte, produce gametes

4. Other structures

capsule, seta, gemma cup, etc.

V. Life cycles of "Bryophytes"

B. Moss example

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IV. Ecology of "Bryophytes"

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A. Asexual reproduction Most bryophyte reproduction is asexual via:

• Fragmentation

• Clonal growth

• Specialized structures

Gemma cups (asexual reproduction)

Fig. 16-13a

B. Habitats

1. In general...

• Wet environments

• Tolerant of dry periods

• Soil not required

Microenvironment:

small area distinct from surrounding landscape

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• In wet areas: mosses common, liverworts occasional

• North Hills cooler and wetter than South Hills

• Gorges/gullies really wet; example: Spearfish Canyon

2. In the Black Hills... C. Sphagnum moss (aka "peat moss")

1. Characteristics of Sphagnum

• Absorbent: 1 (part sphagnum) : 16+ (parts water)

• Acidifying: preserves & slows decomposition

• Anaerobic: slows decomposition

• Peat: layers of undecomposed Sphagnum

2. N. Hemisphere Sphagnum habitat

Fens: less acidicinput: precipitation, groundwater, streams

Bogs: more acidicinput: precipitation only

• Sphagnum: relatively less abundant

• In Black Hills: rare habitat w/ rare plants

Fens Bogs• Sphagnum: dominant

• In Black Hills: absent

• Boreal forest: glaciated northern hemisphere areas

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Bog formation (glaciated lakes) Step 1: (Pothole) lake• Sphagnum grows from edges

• Groundwater feeds lake

Step 2: Floating bog• Sphagnum grows over water

• Peat builds on bottom, blocks groundwater

Loose floating bog (Minnesota 2018)

Step 3: Grounded bog• Peat fills lake

• Slow-growing forest develops

Bogs and unusual plants• Acid-loving plants

• Carnivorous plants

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Cranberries (acid loving)Sundew (carnivorous) Pitcher plants (carnivorous)

Why are carnivorous plants in bogs?• Low nutrient

• Acidic

Bogs and historical artifacts• Bog butter

• Bog bodies

Bog butter

preserved dairy or animal fat(not rancid)

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Bog bodies

8000 YA - 1940s,usually violent deaths

Why did butter and people mummify?• Cold

• Acidic

• Anaerobic

è Very slow decomposition

Peatlands and carbon dioxide• Major carbon sequestration: carbon "locked" in peat

• Unknown peatland amount and location

• Destroyed by agriculture, development, fire