• Terrestrial Adaptations - living on land poses different problems from living in water

– Plants require structural specializations• Roots and shoots

– Shoots » Leaves – photosynthesis and gas exchange» Stems – transport water up and sap down

– Roots – absorb water and dissolved minerals..

Chapter 16 - Plants, Fungi, and the Move onto Land

Alga

Surrounding water supports the alga

Whole alga performs Photosynthesis; absorbs water, CO2, and minerals from the water

Leaves are main photosynthetic organs

Gametangia protect gametes from dehydration; female gametangia protect developing embryosCuticle reduces water

loss

Stomata allow gas exchange between plant and atmosphere

Lignin hardens cell walls

Shoot supports plant; may perform photosynthesis

Vascular tissues transport water, minerals, and sugars; provide support

Roots anchor plant; mycorrhizae (root/fungus associations) help absorb water and minerals from the soil)

True root, stems, and leaves have vascular tissue that form “veins” in the tissues.

•Xylem – transports water and minerals through dead cells that form “straws” in the tissue

•Phloem – living cells that transport sap (sugars in water) throughout the plant..

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Bry

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Origin of plants

Early vascular plants

First seed plants

Diversification of flowering plants

Plant

Diversity

Nonvascular Plants – Bryophytes

•No vascular tissue, must be low to ground, live in moist areas,

no true roots, stems, or leaves

Mosses – the most familiar..

• Plants, including mosses, have two distinct versions of the plant

– The gametophyte, which produces gametes

– The sporophyte, which produces spores

(phyte = plant)..

Sporesn Mito

sis

Sporophyte2n

Mitosis

Gametes (sperm and

eggs)n

Fertilization

Zygote2n

Mitosis

Spore capsule

Meiosis

Gametophyten

Haploid

Diploid

• The life cycle of a moss exhibits an alternation of generations

Seedless Vascular Plants - Ferns

•Have vascular tissue; true roots, stems, and leaves; do not produce seeds; have flagellated sperm that swim to ovule

Seed Plants – Gymnosperms & Angiosperms

Seed – embryonic plant with food supply packaged in a protective coat..

Gymnosperms - Conifers

•Most all are evergreens; produce seed cones and pollen cones; sporophyte generation is more prominent than the gametophyte generation..

• Pollen grain– Is actually the much-reduced male

gametophyte– Fertilizes the female gametophyte

• Ovule– Contain the female gametophyte– Will develop into the seed..

Angiosperms– Supply nearly all our food and much of our fiber

for textiles• More efficient water transport and the evolution of

the flower help account for the success of the angiosperms

Integuments

Spore

(a) Ovule

Haploid (n)

Diploid (2n)

Pollen tube

Pollen grain(male gametophyte)

Female gametophyte

Egg nucleus

Discharged sperm nucleus

(b) Fertilized ovule

Seed coat (derived from integuments)

Food supply (derived from female gametophyte tissue)

Spore case

Embryo(new sporophyte)

(c) Seed..

•A characteristic of angiosperms is double fertilization

•One sperm nucleus fertilizes and egg in the female gametophyte = zygote

•One sperm nucleus fertilizes another cell in the female gametophyte (not the egg) = endosperm

This synchronizes the development of the embryo and the food reserves. The entire ovule develops in to a seed.

Mature sporophyte plant with flowers

Germinated pollen grain (male gametophyte) on stigma of carpel

Anther at tip of stamen

Pollen tube growing down style of carpel

Ovary (base of carpel)

Embryo sac (female gametophyte)

Egg

Sperm nuclei

Fertilization

Endosperm

Zygote

Embryo (sporophyte)

Fruit (develops from ovary)

Seed (develops from ovule)

Seed

Germinating seed

Sporophyte seedling

Haploid (n)

Diploid (2n)..

Ovule

Life cycle of Angiosperms

• The dominant stage of the angiosperms is a sporophyte with gametophytes in its flowers

Stamen

Anther

Filament

Ovule

Petal

PistilStigma

Style

Ovary

SepalContains female gametophyte..

Contains male gametophyte = pollen

Flower

•Sepals = outer whorl of modified leaves; protection

•Petals = second whorl of modified leaves; bright, showy; attract pollinators

•Stamen = anther & filament; produces pollen – the male gametophyte

•Pistil = stigma, style, & ovary with ovules; ovules contain the female gametophyte

Fruit = ripened ovary usually containing seeds..