Evolutionary Trends Bryophytes The rise of the vascular plants The rise of the seed plants

Plant groups arise, thrive, and give way to new groups Angiosperms dominate most habitats Gymnosperms dominate some regions, but are threatened by deforestation

Plant groups arise, thrive, and give way to new groups

Angiosperms dominate most habitats

Gymnosperms dominate some regions, but are threatened by deforestation

p.244

General features: -sporic meiosis and general life cycle Phyla grouped into: - Nonvascular plants (lack true (lignified) vascular tissue) - Seedless vascular plants (true vascular tissue (phloem and xylem), but reproduce only by spores (no seeds made) - Seed bearing vascular plants

General features:

-sporic meiosis and general life cycle

Phyla grouped into:

- Nonvascular plants (lack true (lignified) vascular tissue)

- Seedless vascular plants (true vascular tissue (phloem and xylem), but reproduce only by spores (no seeds made)

- Seed bearing vascular plants

Plants arose from a group of algae. One line of green algae gave rise to all plants. Their evolutionary story is one of the increasing adaptation to life in drier environments. 295,000 kinds of plants on Earth. With diverse kingdom, we find recurring structures that correlate with present and past functions.

Plants arose from a group of algae.

One line of green algae gave rise to all plants. Their evolutionary story is one of the increasing adaptation to life in drier environments.

295,000 kinds of plants on Earth.

With diverse kingdom, we find recurring structures that correlate with present and past functions.

Earth’s atmosphere was originally oxygen free Ultraviolet radiation bombarded the surface Photosynthetic cells produced oxygen and allowed formation of protective ozone layer

Earth’s atmosphere was originally oxygen free

Ultraviolet radiation bombarded the surface

Photosynthetic cells produced oxygen and allowed formation of protective ozone layer

Cyanobacteria were probably first to produce oxygen Later, green algae evolved and gave rise to plants

Cyanobacteria were probably first to produce oxygen

Later, green algae evolved and gave rise to plants

Algae are photosynthetic protists, multicellular, eukaryotic, photosynthetic and autotrophic. 1) Rosette-shaped cellulose-synthesizing complex 2) Peroxisome enzymes (minimize the loss of organic products as a result of photorespiration) 3) Structure of flagellated sperm 4) Formation of a phragmoplast (An alignment of cytoskeletal elements and Golgi-derived vesicles that forms across the midline of a dividing plant cell. The cell plate then develops in the middle of the phragmoplast.) 5) Genetic evidence

Algae are photosynthetic protists, multicellular, eukaryotic, photosynthetic and autotrophic.

1) Rosette-shaped cellulose-synthesizing complex 2) Peroxisome enzymes (minimize the loss of organic products as a result of photorespiration) 3) Structure of flagellated sperm 4) Formation of a phragmoplast (An alignment of cytoskeletal elements and Golgi-derived vesicles that forms across the midline of a dividing plant cell. The cell plate then develops in the middle of the phragmoplast.) 5) Genetic evidence

ADVANTAGES: Sunlight unfiltered by water and plankton Atmosphere had more CO2 than water Soil was rich in mineral nutrients Originally relatively few herbivores and pathogens DISADVANTAGES: Relative scarcity of water Lack of structural support against gravity

ADVANTAGES:

Sunlight unfiltered by water and plankton

Atmosphere had more CO2 than water

Soil was rich in mineral nutrients

Originally relatively few herbivores and pathogens

DISADVANTAGES:

Relative scarcity of water

Lack of structural support against gravity

Most plant lineages became structurally adapted to life on land. They have root and shoot systems, a waxy cuticle, stomata, vascular tissues and lignin-reinforced tissues. Sporophytes with well-developed roots, stems and leaves came to dominate the life cycles of most land plants. Parts of these complex sporophytes nourish and protect the new generation until conditions favor for dispersal and growth.

Most plant lineages became structurally adapted to life on land.

They have root and shoot systems, a waxy cuticle, stomata, vascular tissues and lignin-reinforced tissues.

Sporophytes with well-developed roots, stems and leaves came to dominate the life cycles of most land plants.

Parts of these complex sporophytes nourish and protect the new generation until conditions favor for dispersal and growth.

Root systems – underground absorptive structures evolved as plants colonized the land Shoot systems – evolved where stems and leaves intercepted sunlight energy and took in CO2 from the air.

Root systems – underground absorptive structures evolved as plants colonized the land

Shoot systems – evolved where stems and leaves intercepted sunlight energy and took in CO2 from the air.

Vascular tissues - evolution of roots and shoots forming components – xylem and phloem for transporting water and sugars to all tissues. Waxy cuticle – evolved to assist plant to conserve water on dry, hot days. Stomata – evolved to allow control of water loss and transport of gases.

Vascular tissues - evolution of roots and shoots forming components – xylem and phloem for transporting water and sugars to all tissues.

Waxy cuticle – evolved to assist plant to conserve water on dry, hot days.

Stomata – evolved to allow control of water loss and transport of gases.

Gametophyte Haploid gamete producing body Sporophyte Diploid product of fused gametes Spore Resting structure The most recently evolved groups produce seeds and pollen grains which were the key innovations that allowed the seed plants to spread widely into diverse habitats.

Gametophyte

Haploid gamete producing body

Sporophyte

Diploid product of fused gametes

Spore

Resting structure

The most recently evolved groups produce seeds and pollen grains which were the key innovations that allowed the seed plants to spread widely into diverse habitats.

The generation in the life cycle of a plant that produces spores. Is diploid but its spores are haploid. Either completely or partially dependent on the gametophyte generation in mosses and liverworts, but is the dominant plant in the life cycle of clubmosses, horsetails, ferns and seed plants.

The generation in the life cycle of a plant that produces spores.

Is diploid but its spores are haploid.

Either completely or partially dependent on the gametophyte generation in mosses and liverworts, but is the dominant plant in the life cycle of clubmosses, horsetails, ferns and seed plants.

Polytrichum commune, hairy cap moss Sporophyte Gametophyte

mitosis zygote (2 n ) multicelled sporophyte (2 n ) fertilization meiosis gametes (2 n ) spores (2 n ) multicelled gametophytes ( n ) mitosis mitosis Diploid Haploid Fig. 15-2, p.245 Plant Life Cycles

Majority of plants Have internal tissues that carry water and solutes Two groups Seedless vascular plants Seed-bearing vascular plants

Majority of plants

Have internal tissues that carry water and solutes

Two groups

Seedless vascular plants

Seed-bearing vascular plants

zygote SPOROPHYTE (2 n ) GAMETOPHYTE ( n ) GREEN ALGAE BRYOPHYTE FERN GYMNOSPERM ANGIOSPERM Relative size Life span

Most algae and all bryophytes put more energy into gamete-producing structures. Other groups evolved in seasonally dry habitats on land and they put most energy into complex structures to produce spores, and also to retain , nourish, and protect gametes through harsh conditions.

Most algae and all bryophytes put more energy into gamete-producing structures.

Other groups evolved in seasonally dry habitats on land and they put most energy into complex structures to produce spores, and also to retain , nourish, and protect gametes through harsh conditions.

Nonvascular plants Bryophytes Vascular plants Seedless Seed-bearing

Nonvascular plants

Bryophytes

Vascular plants

Seedless

Seed-bearing

charophytes bryophytes lycophytes horsetails cycads ginkgos conifers gnetophytes flowering plants seed plants plants with true leaves vascular plants land plants (closely related groups) Fig. 15-4, p.246 ferns An evolutionary trees for plants showing monophyletic groups

Land plants have specialized gametes (egg, sperm). Sperm must swim in water to reach egg. Land plants have specialized gametangia (antheridia and archegonia). Most of plants that do not have specialized gametophytes are homosporous plants  make one kind of meiospore. Heterosporous plants make 2 types of meiospores: - male gametophyte that produces sperm - female gametophyte that produces eggs Thus, forming specialized spores and specialized gametophytes.

Land plants have specialized gametes (egg, sperm). Sperm must swim in water to reach egg.

Land plants have specialized gametangia (antheridia and archegonia).

Most of plants that do not have specialized gametophytes are homosporous plants  make one kind of meiospore.

Heterosporous plants make 2 types of meiospores:

- male gametophyte that produces sperm

- female gametophyte that produces eggs

Thus, forming specialized spores and specialized gametophytes.

Pollen grains Arise from megaspores Develop into male gametophytes Can be transported without water Seeds Embryo sporophyte inside nutritive tissues and a protective coat Withstand hostile conditions

Pollen grains

Arise from megaspores

Develop into male gametophytes

Can be transported without water

Seeds

Embryo sporophyte inside nutritive tissues and a protective coat

Withstand hostile conditions

Bryophytes 24,000 species Three groups /phyla: -Mosses (Bryophyta) -Liverworts (Hepaticophyta) -Hornworts (Antherocerophyta)

Bryophytes

24,000 species

Three groups /phyla:

-Mosses (Bryophyta)

-Liverworts (Hepaticophyta)

-Hornworts (Antherocerophyta)

A gamete-forming body (gametophyte) dominates their life cycle. Nonvascular (no specialized tissues to distribute water and sugars, so plants remain small in size). Rhizoids (rudimentary rootlike organs) to absorb water and minerals and to attach gametophytes to soil Usually live in damp habitats, from fresh water to rock surfaces.

A gamete-forming body (gametophyte) dominates their life cycle.

Nonvascular (no specialized tissues to distribute water and sugars, so plants remain small in size).

Rhizoids (rudimentary rootlike organs) to absorb water and minerals and to attach gametophytes to soil

Usually live in damp habitats, from fresh water to rock surfaces.

Moss plants Peat moss ( Sphagnum ) Liverwort, Marchantia has male and female parts on different plants

Waxy cuticle conserves water Cellular jacket around gamete-producing parts Sporophyte draws nutrients from gametophytes Flagellated sperm require water to reproduce

Waxy cuticle conserves water

Cellular jacket around gamete-producing parts

Sporophyte draws nutrients from gametophytes

Flagellated sperm require water to reproduce

Shows marked alternation of generations between gametophyte and sporophyte. Possess erect or prostrate leafy stems (gametophyte(n) generation) which give rise to leafless stalks bearing capsules (sporophyte(2n) generation) that are dependent on water and nutrients. Spores formed in capsules are released and grow to produce new plants.

Shows marked alternation of generations between gametophyte and sporophyte.

Possess erect or prostrate leafy stems (gametophyte(n) generation) which give rise to leafless stalks bearing capsules (sporophyte(2n) generation) that are dependent on water and nutrients.

Spores formed in capsules are released and grow to produce new plants.

Zygote grows, develops into a sporophyte while still attached to gametophyte. fertilization zygote sperm-producing structure egg-producing structure Diploid Stage Haploid Stage mature sporophyte meiosis Spores germinate. male gametophyte female gametophyte

9500 sp. 3 classes : - Sphagnidae (peat moss) - Andreaeidae (granite moss) - Bryidae (true moss)

9500 sp.

3 classes :

- Sphagnidae (peat moss)

- Andreaeidae (granite moss)

- Bryidae (true moss)

1 living genus Sphagnum , 150 sp., diverged early Wet areas (i.e., bogs), dense clumps Commercial value

1 living genus Sphagnum , 150 sp., diverged early

Wet areas (i.e., bogs), dense clumps

Commercial value

A peat bog. Gametophyte Sporangium at tip of sporophyte Living photo- synthetic cells Dead water- storing cells 100 µm Closeup of Sphagnum. Note the “leafy” Gametophytes and their offspring, the sporophytes. Sphagnum “leaf” (LM). The combination of living photosynthetic cells and dead water-storing cells gives the moss its spongy quality. “ Tolland Man,” a bog mummy dating from 405–100 B.C. The acidic, oxygen-poor conditions produced by Sphagnum can preserve human or animal bodies for thousands of years. Sphagnum, or “peat moss,” forms extensive deposits of partially decayed organic material known as peat Sphagnum plays an important role in the Earth’s carbon cycle

Distinctive characteristics protonema (young gametophyte) is platelike, 1 cell thick and with marginal meristem gametophyte stems bear 5 branches/ node thus moplike leaves 1 cell thick w/ living cells surrounding large dead patches perforated stems and dead leaf cells = high water holding capacity, 20x dry wt used as diaper absorbant, wound dressing decay resistant, lowers pH explosive operculum Used as fuel, potting media Peatlands = 1% Earth surface stores 400 B metric tons C

Distinctive characteristics

protonema (young gametophyte) is platelike, 1 cell thick and with marginal meristem

gametophyte stems bear 5 branches/ node

thus moplike

leaves 1 cell thick w/ living cells surrounding large dead patches

perforated stems and dead leaf cells = high water holding capacity, 20x dry wt

used as diaper absorbant, wound dressing

decay resistant, lowers pH

explosive operculum

Used as fuel, potting media

Peatlands = 1% Earth surface

stores 400 B metric tons C

2 genera Blackish-green/dark reddish-brown Lives on granite or calcareous rocks in mtns or artic Slits in capsule = spore discharge

2 genera

Blackish-green/dark reddish-brown

Lives on granite or calcareous rocks in mtns or artic

Slits in capsule = spore discharge

Greatest diversity, “true mosses” Have rhizoids Unisexual/bisexual Fertilized with water, wind, insects Sporophyte on top of gametophyte Sporangia mature 6-18 months. Also capable of fragmentation.

Greatest diversity, “true mosses”

Have rhizoids

Unisexual/bisexual

Fertilized with water, wind, insects

Sporophyte on top of gametophyte

Sporangia mature 6-18 months.

Also capable of fragmentation.

Moss lifecycle ♂ and ♀ gametangia dependent sporophyte spore dispersal

Spores germinate into protonema (gametophyte)

Spores germinate into protonema (gametophyte)

‘ Leafy shoot’ growing from branched protonema

Moss lifecycle ♂ and ♀ gametangia dependent sporophyte spore dispersal

Archegonia in archegonial head Anthredia in anthredial head

Antheridium and antheridia head of Mnium

Neck cells Egg within the archegonium Stalk of archegonium

Sporophyte Gametophyte

Peristome = cap of sporangium (capsule) rings of teeth uncurl when dry to release spores in dry conditions unique to Bryidae

Peristome = cap of sporangium (capsule)

rings of teeth uncurl when dry to release spores in dry conditions

unique to Bryidae

Acidic metabolic products hamper bacterial and fungal decomposers’ growth. “ decay is delayed” Has antiseptic properties and high absorbency )5x times more water than cotton)– used as substitute for bandages.

Acidic metabolic products hamper bacterial and fungal decomposers’ growth.

“ decay is delayed”

Has antiseptic properties and high absorbency )5x times more water than cotton)– used as substitute for bandages.

6 000 species Liverwort gametophytes are either thalloid or leafy Thallus – flattened lobed body form Rhizoids anchor liverwort to soil “ leafy” liverworts resemble mosses Lack stomata, vascular tissue and true roots Moist environments Reproduce asexually and sexually Gemmae – asexual reproduction (tiny balls of tissue that disperse and grow) Thallus – branches and grows

6 000 species

Liverwort gametophytes are either thalloid or leafy

Thallus – flattened lobed body form

Rhizoids anchor liverwort to soil

“ leafy” liverworts resemble mosses

Lack stomata, vascular tissue and true roots

Moist environments

Reproduce asexually and sexually

Gemmae – asexual reproduction (tiny balls of tissue that disperse and grow)

Thallus – branches and grows

They are named liverworts because ancient people thought they resembled a liver and could be used to cure liver ailments.

They are named liverworts because ancient people thought they resembled a liver and could be used to cure liver ailments.

Seven orders in one class Order Marchantiales Order Metzgeriales Order Jungermanniales

Seven orders in one class

Order Marchantiales

Order Metzgeriales

Order Jungermanniales

Growth occurs by division of an apical cell. The thallus has an inverted Y shaped and its dorsal surface has large air chambers. The gametophyte differentiates gametes in gametangia. Male- antheridium ; Female- archegonium Ricciocarpus – monoecius  protoandrus Both male and female contain sterile cells. The sporophyte is not well differentiated.

Growth occurs by division of an apical cell.

The thallus has an inverted Y shaped and its dorsal surface has large air chambers.

The gametophyte differentiates gametes in gametangia.

Male- antheridium ; Female- archegonium

Ricciocarpus – monoecius  protoandrus

Both male and female contain sterile cells.

The sporophyte is not well differentiated.

Marchantia foliacea

Marchantia berteroana

Gametangium (pl. gametangia)- Multicellular plant structure in which gametes are formed. Female gametangia are called archegonia, and male gametangia are called antheridia. Archegonium (pl. archegonia)- In plants, the female gametangium, a moist chamber in which gametes develop. Antheridium (pl. antheridia)- In plants, the male gametangium, a moist chamber in which gametes develop.

Gametangium (pl. gametangia)- Multicellular plant structure in which gametes are formed. Female gametangia are called archegonia, and male gametangia are called antheridia.

Archegonium (pl. archegonia)- In plants, the female gametangium, a moist chamber in which gametes develop.

Antheridium (pl. antheridia)- In plants, the male gametangium, a moist chamber in which gametes develop.

Sporophyte growing from archegoniophores

100 sp., known as horned liverworts Resemble thallus liverwort but produce larger long horn-shaped green sporophytes that split longitudinally to release the spores , and less dependent on gametophyte Each cells contain a single chloroplast (photosynthetic) Some are dioecius, while others have both types of sex organ on the same plant.

100 sp., known as horned liverworts

Resemble thallus liverwort but produce larger long horn-shaped green sporophytes that split longitudinally to release the spores , and less dependent on gametophyte

Each cells contain a single chloroplast (photosynthetic)

Some are dioecius, while others have both types of sex organ on the same plant.

Arose during the Carboniferous era Produce spores but no seeds Groups/Phyla: -Psilophyta (whisk ferns) -Lycophyta (club mosses) -Sphenophyta (horsetails) -Pterophyta (ferns)

Arose during the Carboniferous era

Produce spores but no seeds

Groups/Phyla:

-Psilophyta (whisk ferns)

-Lycophyta (club mosses)

-Sphenophyta (horsetails)

-Pterophyta (ferns)

Simplest vascular plants Small group (about 12 species but most extinct remaining 6 species) Tropical habitats Simple sporophyte bodies: just stems. No leaves or roots Stems with dichotomous branching (evenly split into two smaller stems) (primitive characteristic) Sporangia on aerial stems Underground stems called rhizomes: have filamentous rhizoids. Example: Psilotum

Simplest vascular plants

Small group (about 12 species but most extinct remaining 6 species)

Tropical habitats

Simple sporophyte bodies: just stems.

No leaves or roots

Stems with dichotomous branching (evenly split into two smaller stems) (primitive characteristic)

Sporangia on aerial stems

Underground stems called rhizomes: have filamentous rhizoids.

Example: Psilotum

Psilotum Sporangia with sporogenous cells found at tips of stems Sporogenous cells undergo meiosis to produce haploid spores Spores germinate and produce haploid prothalli (underground) Symbiotic relationship with mycorhizal fungi

Psilotum

Sporangia with sporogenous cells found at tips of stems

Sporogenous cells undergo meiosis to produce haploid spores

Spores germinate and produce haploid prothalli (underground)

Symbiotic relationship with mycorhizal fungi

Lepidodendron Fig. 15-7a, p.249 Carboniferous Lycophytes

Second largest seedless vascular plants group (1,100 species) Sporophytes has tiny leaves ( microphylls ) and branching rhizomes  vascularized roots and stems. Sporangia produced on leaves called sporophylls and sometimes sporophylls clustered into a group called strobilus .

Second largest seedless vascular plants group (1,100 species)

Sporophytes has tiny leaves ( microphylls ) and branching rhizomes  vascularized roots and stems.

Sporangia produced on leaves called sporophylls and sometimes sporophylls clustered into a group called strobilus .

Includes club mosses and ground pines Dominated land through the Carboniferous Period (340-280mya) Some species of Lycopodium are epiphytes : -Sporangia borne on sporophylls -Spores develop into inconspicuous gametophytes Mostly homosporous

Includes club mosses and ground pines

Dominated land through the Carboniferous Period (340-280mya)

Some species of Lycopodium are epiphytes :

-Sporangia borne on sporophylls

-Spores develop into inconspicuous gametophytes

Mostly homosporous

Running Ground Pine ( Lycopodium digitatum ).

Sporophyte is the dominant stage. Gametophyte is independent of the sporophyte. Usually small and insignificant. After fertilization, sporophyte develops on the gametophyte, but soon becomes independent of the gametophyte.

Sporophyte is the dominant stage.

Gametophyte is independent of the sporophyte.

Usually small and insignificant.

After fertilization, sporophyte develops on the gametophyte, but soon becomes independent of the gametophyte.

25 smaller sp. of Equisetum survived at present. Sporophytes have rhizomes and hollow, jointed, silica-containing stems. Some produce spores at tips of stem. Free-living gametophytes develop from the released spores.

25 smaller sp. of Equisetum survived at present.

Sporophytes have rhizomes and hollow, jointed, silica-containing stems.

Some produce spores at tips of stem.

Free-living gametophytes develop from the released spores.

Survived through Devonian and at peak during Carboniferous Only genus is Equisetum : Lives in damp locations and has flagellated sperm Homosporous Has photosynthetic, free-living gametophytes

Survived through Devonian and at peak during Carboniferous

Only genus is Equisetum :

Lives in damp locations and has flagellated sperm

Homosporous

Has photosynthetic, free-living gametophytes

Stem and strobilus of marsh horsetail ( Equisetum palustre )

Largest group (11,000 species) Mainly tropical, but many in temperate zone Make true leaves (megaphylls), stems, roots on sporophyte Gametophytes small, delicate, independent of sporophyte. Sporangia often on underside of leaves Fronds divided into leaflets If in patch, patch called sorus (plural: sori) Some patches covered with tissue (indusium). Strobili at the tips of the nonphotosynthetic fertile stems produce and release spores. The young vegetative stem grows into the bushy form.

Largest group (11,000 species)

Mainly tropical, but many in temperate zone

Make true leaves (megaphylls), stems, roots on sporophyte

Gametophytes small, delicate, independent of sporophyte.

Sporangia often on underside of leaves

Fronds divided into leaflets

If in patch, patch called sorus (plural: sori)

Some patches covered with tissue (indusium).

Strobili at the tips of the nonphotosynthetic fertile stems produce and release spores.

The young vegetative stem grows into the bushy form.

Spores are released. Sporophyte still attached to gametophyte. zygote fertilization Diploid Stage Haploid Stage egg sperm mature gametophyte Spores develop . meiosis Spore germinates . rhizome sorus frond

sorus

Adapted to land Still require water for sexual reproduction

Adapted to land

Still require water for sexual reproduction

Gymnosperms arose first Cycads Ginkgos Gnetophytes Conifers Angiosperms arose later Monocots Dicots

Gymnosperms arose first

Cycads

Ginkgos

Gnetophytes

Conifers

Angiosperms arose later

Monocots

Dicots

Arose about 360 mya. Most successful groups of the plant kingdom in terms of diversity and distribution. Edible treasures from flowering plants

Arose about 360 mya.

Most successful groups of the plant kingdom in terms of diversity and distribution.

They are known for pollen grains that can be dispersed without water. Ovules that mature into seeds Tissues adaptation to dry conditions.

They are known for pollen grains that can be dispersed without water.

Ovules that mature into seeds

Tissues adaptation to dry conditions.

Microspores Develop into pollen grains Immature male gametophyte Megaspores Develop on sporophyte in ovule Female gametophyte Pollination pine pollen grains

Microspores

Develop into pollen grains

Immature male gametophyte

Megaspores

Develop on sporophyte in ovule

Female gametophyte

Pollination

Plants with “naked seeds”. Include diverse types from vines to shrubs to trees. Seeds don’t form inside an ovary Four groups: Conifers Ginkgos Cycads Gnetophytes

Plants with “naked seeds”.

Include diverse types from vines to shrubs to trees.

Seeds don’t form inside an ovary

Four groups:

Conifers Ginkgos

Cycads Gnetophytes

Tropical trees and leathery leafed vines and desert shrubs Resemble flowering plants – closest living relatives. Example : Ephedra viridins. Sporophyte has long tap root and a woody stem with strappy leaves seed bearing strobili like this Welwitschia mirabilis

Tropical trees and leathery leafed vines and desert shrubs

Resemble flowering plants – closest living relatives.

Example : Ephedra viridins.

Sporophyte has long tap root and a woody stem with strappy leaves seed bearing strobili like this Welwitschia mirabilis

130 sp made it to the present. Pollen bearing and seed bearing come from separate plants. Most sp. live in tropical and subtropical regions.

130 sp made it to the present.

Pollen bearing and seed bearing come from separate plants.

Most sp. live in tropical and subtropical regions.

Only one sp. still survives– Gingko biloba Deciduous and shed their leaves on the fall. Male plants have fan-shaped leaves resistant to insects and disease , tolerate air pollutants. Female plants have fleshy seed (plum size) and offensive smell as they decay.

Only one sp. still survives– Gingko biloba

Deciduous and shed their leaves on the fall.

Male plants have fan-shaped leaves resistant to insects and disease , tolerate air pollutants.

Female plants have fleshy seed (plum size) and offensive smell as they decay.

Most diverse Mostly woody trees or shrubs with needlelike leaves Shed leaves all year long Few are deciduous Have true cones – clusters of woody scales exposed ovules on upper surface

Most diverse

Mostly woody trees or shrubs with needlelike leaves

Shed leaves all year long

Few are deciduous

Have true cones – clusters of woody scales exposed ovules on upper surface

Conifer, the ponderosa pine Female cone Male cone

Most diverse gymnosperms Woody trees or shrubs Most are evergreen Bear seeds on exposed cone scales Most produce woody cones

Most diverse gymnosperms

Woody trees or shrubs

Most are evergreen

Bear seeds on exposed cone scales

Most produce woody cones

Female cones Clusters of woody scales bearing ovules Megaspores develop into female gametophyte Male cones microspores become pollen grains are not woody

Female cones

Clusters of woody scales bearing ovules

Megaspores develop into female gametophyte

Male cones

microspores become pollen grains

are not woody

section through one ovule ovule one cone scale (houses two ovules) section through a pollen-producing sac one cone scale (houses a pollen-producing sac) meiosis fertilization seed coat embryo zygote mature sporophyte seedling pollen tube sperm-producing cell eggs female gametophyte pollination microspores form megaspores form seed Diploid Haploid Pine Life Cycle

Only angiosperms produce specialized reproductive structures called flowers. The enlarged base of the flower, the ovary is where the ovules and the seeds develop. Most successful plants in terms of diversity, numbers and distribution. Most sp. coevolved with animal pollinators. Monocots and eudicots are two most diverse lineages.

Only angiosperms produce specialized reproductive structures called flowers.

The enlarged base of the flower, the ovary is where the ovules and the seeds develop.

Most successful plants in terms of diversity, numbers and distribution.

Most sp. coevolved with animal pollinators.

Monocots and eudicots are two most diverse lineages.

stamen (microspores form here) carpel (megaspores form here) petal sepal ovule in an ovary Fig. 15-14, p.254 Angiosperms (Flowering Plants) Flowers Ovules and (after fertilization) seeds develop in ovary

Flowers

Ovules and (after fertilization) seeds develop in ovary

Flower structure Peduncle

Calyx + Corolla = Perianth Parts of flower Description Function Peduncle Flower stalk -Support in suitable position for visiting insects Receptacle All the flower parts arise at the enlarged apex of the flower -Support all the parts of the flower Calyx / Sepal Modified leaves form the outer part of the flower Can be colorful in some plants -Protect during bud development -Produce carbohydrate during photosynthesis -Attraction for pollination Corolla All the petals of a flower Brightly colored to attract insects for pollination Reduced / absent in wind pollinated plants

Reproductive parts Description Function Anther Made up of 4 pollen sacs Each sac produces pollen grains containing male gametes Filament A long slender stalk To support / hold the anthers aloft

Reproductive parts Description Function Ovary A hollow structure containing one or more ovules Each ovule encloses the female gamete, the egg cell Style A long slender stalk A passageway which pollen tube grows towards the ovule Stigma A receptive surface and expanded which often sticky containing nectar The pollen grains adhere / stick to the tip of it

Coevolved with pollinators Three main groups (1) magnoliids (9,200 sp. – magnolias, avocados, nutmeg and peppers) (2) monocots ( 80,000 sp.- orchids, palms, lilies and grasses such as wheat, rice, corn, sugarcane) (3) eudicots (170,000 sp. – herbaceous (nonwoody) plants such as tomatoes, cabbages, roses, daisies, most flowering shrubs and trees and cacti.

Coevolved with pollinators

Three main groups (1) magnoliids (9,200 sp. – magnolias, avocados, nutmeg and peppers) (2) monocots ( 80,000 sp.- orchids, palms, lilies and grasses such as wheat, rice, corn, sugarcane) (3) eudicots (170,000 sp. – herbaceous (nonwoody) plants such as tomatoes, cabbages, roses, daisies, most flowering shrubs and trees and cacti.

Distinctive feature of angiosperms Male gametocyte delivers two sperm to an ovule One fertilizes egg; other fertilizes a cell that gives rise to endosperm

Distinctive feature of angiosperms

Male gametocyte delivers two sperm to an ovule

One fertilizes egg; other fertilizes a cell that gives rise to endosperm

double fertilization meiosis meiosis Microspores -pollen grains female gametophyte pollination Megaspores-undergo mitosis without cytoplasmic division two sperm enter ovule Diploid Haploid sporophyte seed seedling

Table 15-1, p.257

Table 15-2, p.257