bio 1040: plant diversity

Plant

Multicellular eukaryotic autotroph that performs photosynthesis and has an embryo protected by the parent

Plants evolved from

Aquatic algae

Water (for swimming sperm)

Key requirement early plants needed for reproduction

Four main plant groups

Bryophytes, ferns, gymnosperms, angiosperms

Bryophytes

Nonvascular plants (mosses, liverworts, hornworts)

Ferns

Seedless vascular plants

Gymnosperms

Seed plants without flowers (cones)

Angiosperms

Flowering plants

Cuticle

Waxy coating that prevents water loss

Stomata

Pores that regulate gas exchange

Vascular tissue

Transport system (xylem & phloem)

Xylem

Transports water and minerals upward

Phloem

Transports sugars (both directions)

Lignin

Strengthens plant cell walls for support

Seeds

Protect embryos and allow dormancy

Flowers & fruits

Aid in reproduction and dispersal

Alternation of generations

Life cycle with both haploid and diploid multicellular stages

Gametophyte (n)

Produces gametes via mitosis

Sporophyte (2n)

Produces spores via meiosis

Examples of bryophytes

Mosses, liverworts, hornworts

Key features of bryophytes

No vascular tissue, no true roots/stems/leaves

Habitat of bryophytes

Moist environments

Dominant generation in bryophytes

Gametophyte

Advantage of vascular tissue

Allows plants to grow taller and transport materials

Xylem flow direction

One-way (upward)

Phloem flow direction

Two-way

Dominant generation in ferns

Sporophyte

Gametophyte in ferns

Small and short-lived

Fern reproduction requires

Water (sperm swims to egg)

Limitations of spores

No protection, low survival, need water, no stored nutrients

Advantages of seeds

Protection, stored food, dormancy

Seed contains

Embryo, food supply, protective coat

Pollen

Male gametophyte in a protective casing

Function of pollen

Allows fertilization without water

Gymnosperms produce

Seeds (no flowers or fruits)

Example of gymnosperms

Conifers

Gymnosperm reproduction

Pollen fertilizes ovules in cones

Pollination method

Wind

Why angiosperms are successful

Fast reproduction, animal pollination, rapid seed development

Stamen

Male reproductive structure

Anther

Produces pollen

Filament

Supports anther

Carpel (pistil)

Female reproductive structure

Stigma

Sticky surface that catches pollen

Style

Tube connecting stigma to ovary

Ovary

Contains ovules (eggs)

Ovule

Becomes seed after fertilization

Petals

Attract pollinators

Sepals

Protect flower bud

Pollination

Transfer of pollen to stigma

Double fertilization

One sperm → zygote, one sperm → endosperm

Endosperm

Provides nutrients to embryo

Fruit

Mature ovary that protects seeds

Seed dispersal methods

Animals, wind, water