Plant Biology Summary

Angiosperms (Phylum Angiospermophyta)

• Covered seeds, also known as flowering plants.

• Seeds are contained in a protective wall (fruit).

• Most successful plant division (~90% of Kingdom Plantae, ~300,000 species).

• Two subclasses:

  • Monocots: One embryonic leaf (cotyledon).

  • Dicots: Two embryonic leaves (cotyledons).

Monocots vs. Dicots

• Cotyledons:

  • Monocots: One

  • Dicots: Two

• Flower Petals:

  • Monocots: Multiples of 3

  • Dicots: Multiples of 4 or 5

• Leaf Venation:

  • Monocots: Parallel veins

  • Dicots: Branched veins

• Vascular Bundles in Stems:

  • Monocots: Scattered

  • Dicots: Arranged in a ring

• Roots:

  • Monocots: Fibrous

  • Dicots: Taproots

Flower Structure

• Reproductive organs of angiosperms with four specialized leaves:

  • Sepal: Encloses and protects the flower.

  • Petals: Bright colors to attract pollinators.

  • Stamen (male): Filament and anther (anther produces pollen).

  • Carpel (female): Pistil (ovary, style, stigma).

    • Ovary: Produces ovules.

    • Style: Stalk for sperm travel.

    • Stigma: Sticky pad for pollen attachment.

Patterns of Growth

• Annuals: One growing season. (Snapdragons, dandelions)

• Biennials: Two growing seasons. (carrots)

• Perennials: More than two growing seasons. (peonies, lilies, trees)

Coevolution of Flowering Plants and Animals

• Flower Pollination: (moving pollen)

  • Wind: Simple flowers, no fragrance.

  • Animal: Mutualistic symbiosis (bees, birds, mammals).

• Mutualistic Symbiosis

  • Animal gains food

  • Flower gains the ability to spread genes

• Seed Dispersal:

  • Goal: Distribute seeds away from parent plant to avoid competition

  • Adaptations:

    • Wind: Fruit can be carried by wind.

    • Water: Seeds can float.

    • Animals: Seeds attach or are eaten and dispersed.

Roots

• Function: Absorb water and minerals, anchor plants.

• Structure:

  • Taproot: Thick primary root with secondary root hairs. (carrots & radish)

  • Fibrous: Equally branching secondary roots. (grass & lilies)

• Root Parts:

  • Epidermis: Protection, absorbs water and minerals.

  • Cortex: Storage, transports water to xylem.

  • Parenchema cells: unspecialized cells; create bulk

  • Endodermis: Controls water flow, filters with Casparian strip (prevents backflow)

  • Vascular tissue: xylem (moves water), phloem (moves food).

• Growth: Radicle emerges, grows downwards (positive gravitropism).

Stems

• Function: Supports the leaves, moves water and nutrients.

• Structure:

  • Pith: Storage.

  • Vascular tissue: xylem & phloem.

  • Cork: Protection.

• Stem Parts:

  • Vascular cambium: Makes xylem and pholem.

  • Sapwood: Young xylem, transports water.

  • Heartwood: Old xylem, structural support.

  • Cork cambium: Makes cork.

• Growth:

  • Apical meristem: Grows in length.

  • Vascular cambium: Grows in width (vascular tissue).

  • Cork cambium: Forms epidermis (bark).

Leaves

• Function: Photosynthesis CO2 + H2O —> C6H12O6 + O2 .

• Structure:

  • Petiole: Connects leaf to stem.

  • Cuticle: Reduces water loss.

  • Epidermis: Protection, makes cuticle.

  • Mesophyll:

    • Palisade: Photosynthesis.

    • Spongy: Gas exchange.

  • Vascular bundle (vein): xylem and phloem.

  • Stomata: Pores for gas exchange.

  • Guard cells: Open/close stomata.

• Leaf shapes:

  • Blade-shaped (broadleaf): maple & roses

  • Needle-shaped (conifers): fir & pine

Kingdom Plantae

• Multicellular eukaryotes with cellulose cell walls.

• Autotrophic (mostly), converting solar energy into chemical energy.

• Base of terrestrial food chains.

• Evolved from green algae.

• Requirements for life on land and Adaptations:

  • Water: Roots to take in water, transport system (xylem).

  • Nutrients/minerals: Roots to transport.

  • Food transport: Stem (pholem tisssue).

  • Sunlight: Rigid support to align leaves.

  • Prevent water loss: Stomata on underside of leaves.

  • Prevent zygote/embryo dry out: Seeds/spores.

General Plant Phyla

• Bryophyta: No seeds (spores), non-vascular (mosses, liverworts, hornworts).

• Pteridophyta: No seeds (spores), vascular tissue (ferns, horsetails).

• Coniferophyta: Seeds, vascular tissue, cones (evergreen trees, pines, cedar).

• Angiospermophyta: Seeds, vascular tissue, flowers (flowering plants, grass, roses).

Bryophytes (Mosses, Liverworts, Hornworts)

• Evolved from green algae.

• Primitive land plants.

• Require wet environments

• No true roots, leaves, or stems.

• Non-vascular (water moves cell to cell by diffusion).

• Life cycle: alternation of generations (haploid gametophyte with diploid sporophyte).

• Flagellated sperm (require water for reproduction)

Vascular Plants

• "True" land plants with true roots, stems, and leaves.

• Transport of water, minerals, and nutrients:

  • Xylem (moves water): tracheid cells & vessels

  • Phloem (moves food): sieve cells

• Body Support: Rigid cell walls (lignin in cellulose).

• Water Loss: Cuticle (waxy material).

• Gas Exchange: Stomata (pores on underside of leaves).

• Reproduction: Dispersal of gametes (wind pollination), multicellular sex organs to protect gametes.

Ferns

• Vascular plants that reproduce with spores.

• True vascular tissue (xylem + pholem).

• Strong, functional roots.

• Rhizomes (underground stems) and rhizoids.

• Fronds (large leaves).

• Require water for reproduction.

Seed Plants

• Do not require water for reproduction.

• Gymnosperms (naked seeds) and Angiosperms (flowering plants).