The Plant Kingdom: The Plant Kingdom: Flowering PlantsFlowering Plants

Chapter 25Chapter 25

LEARNING OBJECTIVE 1LEARNING OBJECTIVE 1

• Summarize the features that Summarize the features that distinguish distinguish flowering plantsflowering plants from from gymnospermsgymnosperms

KEY TERMSKEY TERMS

• ANGIOSPERM ANGIOSPERM • Traditional name for flowering plantsTraditional name for flowering plants• A large, diverse phylum of plants that form A large, diverse phylum of plants that form

flowers for sexual reproduction and produce flowers for sexual reproduction and produce seeds enclosed in fruitsseeds enclosed in fruits

Flowering PlantsFlowering Plants

• Like gymnosperms:Like gymnosperms:• Flowering plants have vascular tissues and Flowering plants have vascular tissues and

produce seeds produce seeds

• Unlike gymnosperms:Unlike gymnosperms:• OvulesOvules of flowering plants are enclosed within of flowering plants are enclosed within

an an ovaryovary

KEY TERMSKEY TERMS

• OVULE OVULE • Structure in the ovary that contains a female Structure in the ovary that contains a female

gametophyte and develops into a seed after gametophyte and develops into a seed after fertilization fertilization

• OVARY OVARY • Base of a carpel or fused carpels that Base of a carpel or fused carpels that

contains ovules and develops into a fruit after contains ovules and develops into a fruit after fertilizationfertilization

Orange Fruit DevelopmentOrange Fruit Development

LEARNING OBJECTIVE 2LEARNING OBJECTIVE 2

• Describe the ecological and economic Describe the ecological and economic significance of the flowering plantssignificance of the flowering plants

Ecology and EconomyEcology and Economy

• Our survival as a species depends on Our survival as a species depends on flowering plants flowering plants • Major food cropsMajor food crops

• Products Products • Cork, rubber, tobacco, coffee, chocolate, Cork, rubber, tobacco, coffee, chocolate,

aromatic oils for perfumes aromatic oils for perfumes • Valuable lumberValuable lumber• Fibers and medicinesFibers and medicines

Economic BotanyEconomic Botany

• Subdiscipline of botany that deals with Subdiscipline of botany that deals with plants of economic importanceplants of economic importance• Most of these are flowering plantsMost of these are flowering plants

LEARNING OBJECTIVE 3LEARNING OBJECTIVE 3

• Distinguish between Distinguish between monocotsmonocots and and eudicotseudicots, the two largest classes of , the two largest classes of flowering plantsflowering plants

• Give specific examples of each classGive specific examples of each class

KEY TERMSKEY TERMS

• COTYLEDON COTYLEDON • The seed leaf of a plant embryo, which may The seed leaf of a plant embryo, which may

contain food stored for germinationcontain food stored for germination

KEY TERMSKEY TERMS

• MONOCOTMONOCOT • One of two main classes of flowering plants; One of two main classes of flowering plants;

monocot seeds contain a single monocot seeds contain a single cotyledoncotyledon • Monocots have floral parts in threes Monocots have floral parts in threes • Monocots include grasses, orchids, irises, Monocots include grasses, orchids, irises,

onions, lilies, palmsonions, lilies, palms

KEY TERMSKEY TERMS

• EUDICOT EUDICOT • One of two main classes of flowering plants; One of two main classes of flowering plants;

eudicot seeds contain two eudicot seeds contain two cotyledonscotyledons • Eudicots have floral parts in fours or fivesEudicots have floral parts in fours or fives• Eudicots include oaks, roses, mustards, cacti, Eudicots include oaks, roses, mustards, cacti,

blueberries, sunflowersblueberries, sunflowers

Monocots and EudicotsMonocots and Eudicots

(a) Monocots, such as this nodding trillium(Trillium cernuum), have their floral parts in threes.Note the three green sepals, three white petals, sixstamens, and three stigmas (the compound pistilconsists of three fused carpels).

Stigmas ofpistil

Anther ofstamen

Sepal

Petal

Fig. 25-2a, p. 488

(b) Most eudicots such as this Tacitusbellus have floral parts in fours or fives.Note the five petals, 10 stamens, and fiveseparate pistils. Five sepals are also presentbut barely visible against the background.

Pistils

Anther ofstamen

Petal

Fig. 25-2b, p. 488

LEARNING OBJECTIVE 4LEARNING OBJECTIVE 4

• Briefly explain the Briefly explain the life cyclelife cycle of a of a flowering plantflowering plant

• Describe Describe double fertilizationdouble fertilization

Life CycleLife Cycle

• Flowering plants undergo an alternation of Flowering plants undergo an alternation of generations:generations:• Sporophyte generation is larger and Sporophyte generation is larger and

nutritionally independentnutritionally independent• Gametophyte generation is reduced to only a Gametophyte generation is reduced to only a

few microscopic cells few microscopic cells

KEY TERMSKEY TERMS

• DOUBLE FERTILIZATIONDOUBLE FERTILIZATION • A process in the flowering plant life cycle in A process in the flowering plant life cycle in

which there are two fertilizations which there are two fertilizations • One results in formation of a zygote One results in formation of a zygote • Second results in formation of Second results in formation of endospermendosperm

KEY TERMSKEY TERMS

• ENDOSPERMENDOSPERM • The 3The 3nn nutritive tissue formed at some point in nutritive tissue formed at some point in

the development of all angiosperm seedsthe development of all angiosperm seeds

Life Cycle: Flowering PlantsLife Cycle: Flowering Plants

Flower of maturesporophyte

Seedling

Fruit

Seed coatSeed

Embryo

Zygote (2n)

Endosperm (3n)

Anther

Megasporangium(ovule)

Megaspore mother cell

Ovary DIPLOID (2n)SPOROPHYTEGENERATION

HAPLOID (n)GAMETOPHYTEGENERATION

MegasporeEggnucleus

Double fertilization

Two spermcells

Pollentube

Polarnuclei

Embryo sac (maturefemale gametophyte)

Developing pollentube of maturemale gametophyte

Pollination

Pollen grain(immature malegametophyte)

Each microsporedevelops into apollen grain

Microspore

Tetrad ofmicrospores

Microspore mothercells withinmicrosporangia

Meiosis

1

24

56

3

8

7

Fig. 25-3, p. 490

Pollen GrainsPollen Grains

LEARNING OBJECTIVE 5LEARNING OBJECTIVE 5

• Discuss some of the evolutionary Discuss some of the evolutionary adaptations of flowering plantsadaptations of flowering plants

Adaptations of Flowering Plants 1Adaptations of Flowering Plants 1

• Reproduce sexually by forming flowersReproduce sexually by forming flowers

• Form seeds within fruits Form seeds within fruits after double after double fertilizationfertilization

Adaptations of Flowering Plants 2 Adaptations of Flowering Plants 2

• Have efficient water-conducting Have efficient water-conducting vessel vessel elementselements in xylem and carbohydrate-in xylem and carbohydrate-conducting conducting sieve-tube elementssieve-tube elements in in phloemphloem

• Have pollen grains transported by wind, Have pollen grains transported by wind, water, insects, other animalswater, insects, other animals

KEY TERMSKEY TERMS

• APOMIXISAPOMIXIS • A type of reproduction in which fruits and A type of reproduction in which fruits and

seeds are formed asexually seeds are formed asexually

Adaptability of Flowering PlantsAdaptability of Flowering Plants

LEARNING OBJECTIVE 6LEARNING OBJECTIVE 6

• Trace the evolution of flowering plants Trace the evolution of flowering plants from gymnosperms from gymnosperms

Evolution of Flowering PlantsEvolution of Flowering Plants

• Probably descended from ancient Probably descended from ancient gymnosperms with specialized featuresgymnosperms with specialized features• leaves with broad, expanded blades and leaves with broad, expanded blades and

closed carpelsclosed carpels

• Probably arose only onceProbably arose only once

Drimys piperitaDrimys piperita Carpel Carpel

(a) The carpel resembles a foldedleaf in which the ovules borne onits upper surface are enclosed.

(b) A cross section of thecarpel, cut along the dashedline in (a).

Stigma

Style

Ovary

Ovules

Stigma

Fusedmargin

Carpel

Fig. 25-6, p. 493

Fossil AngiospermsFossil Angiosperms

(a) The oldest known fossil angiosperm. This fossil ofthe extinct plant Archaefructus shows a carpel-bearingstem. It was discovered in northeastern China and isabout 125 million years old.

(b) The fossilized flower of the extinct plant Archaeanthuslinnenbergeri, which lived about 100 mya. Thescars on the reproductive axis (receptacle) may showwhere stamens, petals, and sepals were originallyattached but abscised (fell off). Many spirally arrangedpistils were still attached at the time this flower wasfossilized.

Ovule

Carpel

Scars onreproductive axis

Pistils

Fig. 25-7, p. 494

Evolution of Flowering PlantsEvolution of Flowering Plants

Basal Angiosperms Core Angiosperms

Evolution ofvessel elements

Evolution offlowering plants

(a) One hypothesis of relationships among the flowering plants, based on fossil and molecular evidence. Amborella, water lilies, and star anise are living plantswhose ancestors apparently branched off the angiosperm family tree early. These early groups were followed by the magnoliids, the monocot branch, and the eudicots.

Am

bo

rella

Wat

er li

lies

Sta

r an

ise

Mag

no

liid

s

Mo

no

cots

Eu

dic

ots

Fig. 25-8, p. 495

LEARNING OBJECTIVE 7LEARNING OBJECTIVE 7

• Distinguish between Distinguish between basal basal angiospermsangiosperms and and core angiospermscore angiosperms

KEY TERMSKEY TERMS

• BASAL ANGIOSPERMBASAL ANGIOSPERM • One of three groups of angiosperms thought One of three groups of angiosperms thought

to be ancestral to all other flowering plants to be ancestral to all other flowering plants

• CORE ANGIOSPERMCORE ANGIOSPERM • Group including most angiosperm speciesGroup including most angiosperm species• Divided into three subgroups: Divided into three subgroups: magnoliids, magnoliids,

monocots,monocots, and and eudicotseudicots

KEY TERMSKEY TERMS

• MAGNOLIID MAGNOLIID • One of the groups of flowering plantsOne of the groups of flowering plants• Core angiosperms once classified as “dicots,” Core angiosperms once classified as “dicots,”

but molecular evidence indicates they are but molecular evidence indicates they are neither eudicots nor monocotsneither eudicots nor monocots

• Includes species in magnolia, laurel, and Includes species in magnolia, laurel, and black pepper families, several related familiesblack pepper families, several related families

LEARNING OBJECTIVE 8LEARNING OBJECTIVE 8

• Briefly describe the distinguishing Briefly describe the distinguishing characteristics and give an example or characteristics and give an example or two of each of the following flowering two of each of the following flowering plant families: plant families: magnolia, walnut, magnolia, walnut, cactus, mustard, rose, pea, potato, cactus, mustard, rose, pea, potato, pumpkin, sunflower, grass, orchid,pumpkin, sunflower, grass, orchid, and and agaveagave

Flowering Plant Families 1Flowering Plant Families 1

• More than 300 families More than 300 families

• Magnolia familyMagnolia family• Important ornamentals and source of timberImportant ornamentals and source of timber• Examples:Examples: southern magnolia, tuliptree southern magnolia, tuliptree

Magnolia FamilyMagnolia Family

Fig. 25-9, p. 497

Flowering Plant Families 2Flowering Plant Families 2

• Walnut familyWalnut family• Provides nuts for food, wood for furniture Provides nuts for food, wood for furniture • Examples:Examples: English walnut, black walnut, pecan English walnut, black walnut, pecan

• Cactus family Cactus family • Important as ornamentalsImportant as ornamentals• Examples:Examples: prickly pear, Christmas cactus prickly pear, Christmas cactus

Walnut FamilyWalnut Family

(a) The pinnately compound leaves and green fruits of black walnut (Juglans nigra) make the tree easy to recognize.

Young tree

Compound leaf

Catkinof maleflowers Fruit

(a drupe)

Fruit with huskremoved to showhard stone

Femaleflowers

Fig. 25-10a, p. 498

Fig. 25-10b, p. 498

Fig. 25-10c, p. 498

Cactus FamilyCactus Family

(c) Cactus flowers contain numerous sepals, petals, andstamens. The compound pistil consists of two to many fusedcarpels. In this photo of a prickly pear cactus (Opuntiahumifusa), the petals, stamens, and stigma are evident.

Stamens

Petals

Stigma

Fig. 25-11c, p. 499

Flowering Plant Families 3Flowering Plant Families 3

• Mustard familyMustard family• Many important food cropsMany important food crops• Examples:Examples: cabbage, broccoli, cauliflower, cabbage, broccoli, cauliflower,

turnip, mustardturnip, mustard

• Rose familyRose family• Commercially important fruits and ornamentalsCommercially important fruits and ornamentals• Examples:Examples: apple, pear, plum, cherry, apricot, apple, pear, plum, cherry, apricot,

peach, strawberry, raspberry, rosepeach, strawberry, raspberry, rose

Mustard FamilyMustard Family

(a) A typical mustard flower, showing thefour petals arranged in the shape of a cross.

Petal

Pistil

Sepal

Stamen

Fig. 25-12a, p. 501

Mustard FamilyMustard Family

Mustard FamilyMustard Family

Mustard FamilyMustard Family

Rose FamilyRose Family

Rose FamilyRose Family

Rose FamilyRose Family

Flowering Plant Families 4Flowering Plant Families 4

• Pea familyPea family• Important food cropsImportant food crops• ExamplesExamples: garden pea, chick pea, green : garden pea, chick pea, green

bean, soybean, lima bean, peanut, red clover, bean, soybean, lima bean, peanut, red clover, alfalfaalfalfa

Pea FamilyPea Family

(a) Part of a common bean (Phaseolus vulgaris)plant, showing flowers and developing fruits.

Remnants of sepals(and sometimes petalsand stamens)

Compound leaf(three leaflets)Young

fruit

Pod (fruit)

Seeds

(c) The bean fruit, a legume, is opened to show the seeds.

Remnants ofstigma and style

(b) Close-up of a bean flower, showingits irregular corolla shape.

Keel (twofused petals)

Wing

Banner

Sepal Corolla

Fig. 25-14a-c, p. 503

Pea FamilyPea Family

Pea FamilyPea Family

Flowering Plant Families 5Flowering Plant Families 5

• Potato familyPotato family• Important food crops and chemicals used as Important food crops and chemicals used as

drugsdrugs• Examples:Examples: potato, tomato, green pepper, potato, tomato, green pepper,

eggplant, petunia, deadly nightshade eggplant, petunia, deadly nightshade (belladonna)(belladonna)

Potato FamilyPotato Family

Flowering Plant Families 6Flowering Plant Families 6

• Pumpkin familyPumpkin family• Food cropsFood crops• Examples:Examples: pumpkins, melons, squashes, pumpkins, melons, squashes,

cucumbers, cantaloupe, honeydew, cucumbers, cantaloupe, honeydew, muskmelon, cucumber, watermelon muskmelon, cucumber, watermelon

Pumpkin FamilyPumpkin Family

(a) Cutaway view of a female squash flower. Notethe inferior ovary located beneath the point ofattachment of the sepals and petals.

Ovary

Style

Stigma

Petalsfused intobell shape

Fig. 25-16a, p. 505

Pumpkin FamilyPumpkin Family

(b) Cutaway view of a male squash flower. Notethe united anthers.

Anthers

Fig. 25-16b, p. 505

Pumpkin FamilyPumpkin Family

Flowering Plant Families 7Flowering Plant Families 7

• Sunflower familySunflower family• One of the largest families of flowering plantsOne of the largest families of flowering plants• Examples:Examples: chrysanthemums, marigolds, chrysanthemums, marigolds,

sunflowers, daisies, and some food plants sunflowers, daisies, and some food plants such as lettuce, globe artichokessuch as lettuce, globe artichokes

Sunflower FamilySunflower Family

a) Head of a sunflower (Helianthus annuus).

Disc floret

Ray floret

Fig. 25-17a, p. 506

(d) Bisexual disc floret.

(c) Female ray floret.

Ovary

Corolla

Anther

Stigmas

Disc floret

Ray floret

Fig. 25-17cd, p. 506

Flowering Plant Families 8Flowering Plant Families 8

• Grass familyGrass family• Most important family of flowering plants from Most important family of flowering plants from

the human standpointthe human standpoint• Examples:Examples: rice, wheat, corn, oats, barley, rye, rice, wheat, corn, oats, barley, rye,

sugarcane, bamboo sugarcane, bamboo

Grass FamilyGrass Family

(a) The growth habit of a representative grass plant. Grass flowers, whichare wind pollinated, are highly modified. Note, for example, the long,feathery stigmas, adapted to efficiently catch wind-borne pollen.

Fibrous rootsystem

StolonRhizome

Sheath

Blade

Inflorescence

Lemma

Reduced petals

Ovary

Featherystigma

Filament

Palea

Anther

Fig. 25-18a, p. 507

Flowering Plant Families 9Flowering Plant Families 9

• Orchid familyOrchid family• One of the largest families of flowering plants; One of the largest families of flowering plants;

contains a greater variety of flowers than any contains a greater variety of flowers than any other familyother family

• Example:Example: the vanilla orchid the vanilla orchid

• Agave familyAgave family• Best known for ornamentalsBest known for ornamentals• Examples:Examples: century plant, sisal hemp, century plant, sisal hemp,

bowstring hempbowstring hemp

Orchid FamilyOrchid Family

(a) The moth orchid (Phalaenopsis hybrid)has photosynthetic aerial roots.

Aerial roots

Fig. 25-19a, p. 509

(b) A Cymbidium hybrid has pseudobulbsthat function as storage organs.

Pseudobulbs

Fig. 25-19b, p. 509

(c) Orchid flowers, such as Dendrobium, aredistinctive in that the third petal forms a lip.

Lip (modifiedpetal)

Sepal

Petal

Fig. 25-19c, p. 509

Agave FamilyAgave Family

Animation: Monocot Life CycleAnimation: Monocot Life Cycle

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