Plant kingdom diversity Chapters 20-22 Created by Kevin Bleier Milton High School

Characteristics of Plants Autotrophs Multicellular Eukaryotes Plant cell walls made of cellulose

Common Ancestor The common ancestor of ALL plants is thought to be Green Algae In the early evolution of plants, they made the transition from aquatic to land environments

Water is short on land, so relationships like mycorrhizae are important

Cuticle Waxy covering that prevents water loss Crucial for transition to land Also clear … why?

Cladogram Evolution of cuticle (and specialized cells / tissue) Gymnosperms Angiosperms Seedless vascular plants Nonvascular plants Evolution of cuticle (and specialized cells / tissue) Green algae

Plant groups Bryophytes (seedless, non-vascular) Seedless vascular plants Gymnosperms Angiosperms

Bryophytes think moss

Bryophytes Small Found only in damp, moist areas on land 1) Leaves must touch water for photosynthesis 2) Sperm swims through water to reach egg

Bryophytes

Seedless vascular plants Cladogram Gymnosperms Angiosperms Seedless vascular plants Non-vascular plants Evolution of vascular tissue Evolution of cuticle (and specialized cells / tissue) Green algae

Seedless vascular plants Think ferns

Vascular tissue Set of tubes that transport materials around plant Allows plants to grow taller Water travels up through xylem Sugar travels throughout in phloem

Ferns live further on land Mature plant survives fine with vascular tissue But sperm must still swim to egg (needs film of water)

Seedless vascular plants Cladogram Gymnosperms Angiosperms Seedless vascular plants Evolution of pollen grains and seeds Non-vascular plants Evolution of vascular tissue Evolution of cuticle (and specialized cells / tissue) Green algae

Gymnosperms Think cones (any conifer like pine trees) female ovary male pollen cone

Gymnosperms Examples: Spruce Tree, Fir Tree, Pine Tree

Key Adaptations Over Seedless Plants Seeds Pollen Grains

Pollen grains Small and lightweight with sperm inside Removes water requirement for fertilization

Gymnosperm pollen strategy Release a lot, hope some pollinate (Meanwhile, irritating everyone else)

After pollen lands … Builds pollen tube inside female structure to reach egg Sperm still swims to egg inside plant

Seeds Tough coat protects newly fertilized zygote Also contains supply of food to survive for a long time without growing (= dormancy) Overall purpose – increases chances that offspring eventually grow

Seed Dispersal Plants try to disperse offspring far away so they have a higher chance of survival. Dispersal of seeds prevents competition for water, nutrients, light, and living space.

Seed Dispersal Dispersal by wind – wing-like structures, parachute-like structures

Seed Dispersal Dispersal by animals – fruits have hooks that cling on animals fur, other fruits provide food for animals

Seed Dispersal Seeds dispersal is completed by birds, small animals, wind, and water The tough, fibrous outer covering of a coconut provides protection as well as a floatation device

Gymnosperm cones

Full colonization of land Vascular tissue (find water in soil) + Reproduction through air (no need for water for sperm to swim)

Seedless vascular plants Cladogram Gymnosperms Angiosperms Evolution of flowers and fruits Seedless vascular plants Evolution of pollen grains and seeds Non-vascular plants Evolution of vascular tissue Evolution of cuticle (and specialized cells / tissue) Green algae

Angiosperms Think flowers (most diverse plant group) If you eat it, it’s an angiosperm plant

Flowers (key adaptation over gymnosperms) Attract animals to help carry pollen to the next flower Color or scent attractors guide animals to obtain sugar from plant Pollinators also brush by pollen, get on body Overall purpose: reduces amount of pollen that plant has to make (not random wind travel)

Pollinators

Advertising in UV color

After fertilization, ovary becomes fruit

Fruits Overall purpose: Help get seeds far away from parent plant (why?) Many are sugary fruits – animals eat, seeds pooped out far away from parent (and with free fertilizer!) Other fruits use wind (dandelion fruits), water (coconut fruits)

Seedless vascular plants Cladogram Gymnosperms Angiosperms Evolution of flowers and fruits Seedless vascular plants Evolution of pollen grains and seeds Non-vascular plants Evolution of vascular tissue Evolution of cuticle (and specialized cells / tissue) Green algae

Asexual reproduction Plants can also reproduce asexually Vegetative reproduction is faster than sexual reproduction. Vegetative reproduction is where many plant parts can regrow to make a whole new organism when separated. Examples: Ivy or Potato

Overview of plant organs Our assumption: angiosperms Major organs: 1) Root 2) Stem 3) Leaf 4) Flowers

Root organ Absorption of H2O and nutrients from soil Thick root anchors plant, small hairs increase diffusion Fungus threads also help absorption (symbiosis called _______________ ) mycorrhizae

Modified roots Some species store sugar underground = potato

Stem organ Xylem moves H2O / minerals up to leaves Phloem transports sugar to all cells

Leaf organ Often center of photosynthesis cuticle cuticle stoma (hole) vascular bundle (xylem + phloem) cuticle stoma (hole) guard cells

Photosynthesis and leaves sunlight C6H12O6 H2O CO2 O2 sunlight CO2 + H2O C6H12O6 + O2

stoma Stomata are tiny holes in the cuticle. can open and close allow air to move in and out stoma Let in carbon dioxide and let out oxygen and water Guard cells control when stomata are opened vs. closed

Modified leaves Broad leaves – lots of photosynthesis, but lots of water loss as well Where does this occur? tropical rainforests

Modified leaves Cactus needles – modified leaves lower transpiration water loss – does photosynthesis in stem

Water movement up plant Transpiration creates pull that moves water up a plant

Transpirational pull (leaf air space) hydrogen ____________ bonds form between H2O molecules (roots)

Transpirational pull As H2O transpires, it pulls other H2O molecules up Relies on cohesion between water molecules

Transpirational pull Water moves up plant without energy use “solar-powered” Plants must still control transpiration rate

Moving sugar Phloem right next to xylem Sugar pumped into phloem from leaves, creates __________ solution compared to xylem Water comes in by ___________ hypertonic osmosis

Plant reproduction Recall purpose of seeds in gymnosperms and angiosperms Recall purpose of fruits in angiosperms Seed dormancy and triggers for germination (water, fire, etc)

Growth of plants Meristem tissue – cells specializing in mitosis Plant growth focused on growing taller first – why? Tropisms – directed growth in response to a particular environmental stimulus

Plant tropisms Phototropism – growth in response to light Gravitropism – growth in response to gravity (roots “down”, shoots “up”)