Chapter 23: Invading the Land

were probably the first to spread into and up freshwater streams • Later, and fungi made the journey together • Every plant is descended from of Setting the Stage for

• Earth’s was originally free • radiation bombarded the surface • Photosynthetic cells produced oxygen and allowed formation of a protective ozone layer The Plant

• Nearly all are multicelled

• Vast majority are photoautotrophs

– Energy from sun

from air

– Minerals dissolved in

Fig. 23-2, p.372 Charophytes

Fig. 23-3, p.372 Nonvascular Plants

• Fewer than 19,000 species • Three groups Liverworts Vascular Plants

• Majority of plants • Have internal tissues that carry water and solutes • Two groups – Seedless vascular plants – -bearing vascular plants Seedless Vascular Plants

• Arose during the • Produce but no • Four main groups Whisk Horsetails Ferns

Seedless Vascular Plants

Fig. 23-4a, p.372 Seedless Vascular Plants

Fig. 23-4b, p.372 Seedless Vascular Plants

Fig. 23-4c, p.373 Seed-Bearing Vascular Plants

arose first – – Gnetophytes – • Angiosperms arose later – Monocots – Dicots Seed- Bearing Vascular Plants

Archaeanthus linnenbergeri

Fig. 23-4d, p.373

Gondwana 420 mya 360 mya

Bryophytes Origin of Bryophytes diversify. Vast swamp ; (liverworts) earliest Lycophytes, horsetails, bryophytes, -size appear by seedless ferns undergo early lycophytes, horsetails, 475 mya. vascular adaptive radiations. By 360 ferns dominate. origin plants, in mya, seed plants evolve. of conifers late in the . .

Ordovican Silurian Devonian Carboniferous

505 440 410 360 286

Fig. 23-5a, p.373 Plant Evolution

Pangea 240 mya 65 mya

Origin of ginkgos, Ferns, cycads, conifers Origin of flowering plants cycads. Conifers undergo adaptive by the early . diversify. radiations; by start of Rapid adaptive radiations of most lucophytes Cretaceous, conifers and to dominance in and horsetails by the dominant . nearly all on land. end of

Permian Cretaceous present

286 248 213 145 65

Fig. 23-5b, p.373 Evolutionary Trend

multicelled (2n)


Diploid fertilization Haploid

spores (2n) (2n)

multicelled mitosis mitosis (n)

Fig. 23-6a, p.374 zygote only, no sporophyte

green algae bryophytes ferns gymnosperms angiosperms

Fig. 23-6b, p.374 to Land


systems • Vascular tissues ( and ) • Waxy cuticle Evolutionary Tree for Plants

Nested monophyletic groups

flowering plants green zygophytes, charophytes bryophytes lycophytes horsetails ferns cycads ginkgos conifers gnetophytes algae related groups

seed plants (land plants) vascular plants (closely related groups)

Fig. 23-7, p. 387 p.375 Bryophytes • Small, nonvascular, nonwooody • dominates cycle; has leaflike, stemlike, and rootlike parts • Usually live in wet habitats • Flagellated require water to reach Types of Bryophytes

Mosses (most common)

Liverworts (simplest)


Moss Life Cycle

Zygote grows, mature develops into a sporophyte sporophyte while still attached to gametophyte. zygote Diploid Stage Fertilization Meiosis Haploid Stage

Spores germinate. sperm- producing structure male gametophyte - producing structure gametophyte Fig. 23-8a, p.376 Mosses sporophyte


Fig. 23-9b, p.377 : A Liverwort

• Reproduces asexually by gemmae

• Gametophytes are male or female

Female gametophyte Marchantia: A Liverwort

Fig. 23-10a, p.377 Marchantia: A Liverwort

Female gametophyte Male gametophyte

Fig. 23-10b, p.377 Seedless Vascular Plants

• Like bryophytes – Live in wet, humid places – Require water for fertilization • Unlike bryophytes – Sporophyte is free-living and has vascular tissues Seedless Vascular Plants

Lycophytes (Lycophyta) Whisk ferns (Psilophyta) Horsetails (Sphenophyta) Ferns (Pterophyta) Seedless Vascular Plants

Fig. 23-11a, p.378 Seedless Vascular Plants

Fig. 23-11b, p.378 Seedless Vascular Plants

Fig. 23-11c, p.378 Seedless Vascular Plants

Fig. 23-11d, p.378 Ferns (Pterophyta)

• 12,000 species, mostly tropical • Most common sporophyte structure – Perennial underground stem () – and arise from rhizome – Young fronds are coiled “” – Mature fronds divided into leaflets – Spores form on lower surface of some fronds Life Cycle

Sporophyte still attached to gametophyte

zygote rhizome Diploid Stage fertilization meiosis Haploid Stage Spores Spores develop are egg released


Fig. 23-12 mature p. 391 gametophyte germinates p.379 Carboniferous

• Giant lycophytes and horsetails

level and fell repeatedly

• Remains of swamp forests were repeatedly submerged and compressed

• Formation of Carboniferous

Lepidodendron a tree-sized club

Fig. 23-13a, p.380 Carboniferous

Fig. 23-13b, p.380 Carboniferous

stem of a giant seed fern (Medullosa), one of the early seed- stem of giant horsetail () bearing plants ()

Fig. 23-13c, p.380 Rise of Seed-Bearing Plants

• Seeds appeared about 360 million years ago • Seed ferns and gymnosperms were dominant at first • Angiosperms arose later Seed-Bearing Plants • that give rise to grains • inside • More water-conserving than seedless vascular plants Pollen

• Pollen grains are sperm-bearing male gametophytes that develop from microspores • Allows transfer of sperm to egg without water • Can drift on air currents or be carried by Pollen

pollen grains

p.381 Ovules

• Female reproductive structures that become seeds • Consist of: – Female gametophyte with egg -rich – Jacket of cell layers that will form seed coat Ovules

Fig. 23-14a, p.381 Gymnosperms

• Plants with “naked seeds” • Seeds don’t form inside an • Four groups Conifers Ginkgos Cycads Gnetophytes Characteristics

• Widest known, largest number of living species • Woody trees or • Most are • Most produce woody cones Conifer Characteristics

Fig. 23-15a, p.382 Conifer Characteristics

Fig. 23-15b, p.382 Conifer Characteristics

Fig. 23-15c, p.382 Conifer Characteristics

Fig. 23-15d, p.382 Conifer Characteristics

Fig. 23-15e, p.382 Conifer Characteristics

Fig. 23-15f, p.382 Conifer Characteristics

Fig. 23-15g, p.382 Conifer Characteristics

Fig. 23-15h, p.382 Cycads

• Most diverse during age of • Only 100 living species • Palmlike appearance • Pollen-bearing and seed- bearing cones on different plants

Strobilus of a “female” section through one (the red “cut” in the diagram to the left):

surface view of a ovule female cone scale (houses two ovules) section through a pollen sac (red cut) surface view of a scale of a male strobilus mature seed coat (houses two sporophyte pollen sacs) nutritive tissue zygote seed formation Diploid Stage fertilization meiosis meiosis Haploid Stage

sperm- (view inside an Microspores Megaspores ( deposits form, develop form; one producing cell ovule) pollen grain into pollen grains.develops into the near ovule) female gametophyte. Germinating pollen grain (the male eggs gametophyte). Sperm nuclei form as the pollen tube grows toward the egg. female gametophyte Fig. 23-16, p.383 Ginkgos

• Diverse during age of dinosaurs • One surviving species, biloba • trees are male or female

3 Genera of Gnetophytes

• Ephedra

Sporophyte of Ephedra

section surface view of one cone scale through one ovule (houses a pollen-producing sac)

Pine Life Cycle ovule

surface view of one cone scale (houses two ovules)

mature sporophyte seed section through a pollen- coat producing sac zygote seeding embryo Diploid seed fertilization meiosis pollen tube Haploid microspores eggs form sperm-producing megaspores cell pollination form female gametophyte

Fig. 23-16, p. 396 Conifer Distribution

• Reproduce more slowly than angiosperms; at competitive disadvantage in many habitats

• Still dominate in far north, at higher elevations, and in certain parts of Angiosperms

• Flowering plants

• Dominant land plants (260,000 species)

• Ovules and (after fertilization) seeds are enclosed in an ovary

• Three main groups: , monocots, and Angiosperms

Fig. 23-17a, p.384 250 Angiosperms

angiosperms 200 (flowering plants)

150 Number genera of

cycads 100


50 gymnosperms

ginkgo other genera 0 160 140 120 100 80 60 Time (millions of years) Fig. 23-17b, p.384 Angiosperm Evolutionary Tree

water star lilies anise magnoliids monocots eudicots

groups Fig. 23-19, p. 385

(microspores form here) carpel ovule in an (megaspores form ovary here)

Fig. 23-18, p.384 Fig. 23-19a, p.385 Fig. 23-19b, p.385 Fig. 23-19c, p.385 Fig. 23-19d, p.385 Fig. 23-19e, p.385 sporophyte


Plant Life Diploid Meiosis Meiosis Haploid Cycle mitosis without microspores pollination cytoplasmic

two sperm enter ovule female gametophyte Fig. 23-20, p. 399 People and Plants

• Plant began about 11,000 years ago

• About 3,000 species have been used as

• Now about 200 plants are major Nonfood Uses of Plants

, paper, and fuel • Furniture • Rope • Thatched roofing • Natural • Drugs Plants of Abuse

• Tobacco plants are Nicotiana sp. • Cannabis sativa is source of marijuana • Coca are used to produce cocaine • Toxic plant alkaloids, such as henbane and belladona, have been used as poisons and as medicine

• Deforestation is the mass removal of all trees from large tracts for logging, , and

• Greatest in Brazil, , , and

• Sustainable development Deforestation

Fig. 23-23b, p.389