K: Plantae = The Land Plants. What is a plant? Multicellular autotroph? With complex tissues?
Plants The Kingdom Plantae. Common characteristics 1.Multicellular 2.Eukaryotic 3.Photoautotrophic.
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Transcript of Plants The Kingdom Plantae. Common characteristics 1.Multicellular 2.Eukaryotic 3.Photoautotrophic.
First: Some terms to know
• Gametophyte: a multi-celled haploid body (stage) that produces haploid (n) gametes.
• Zygote: a diploid body formed when gametes fuse at fertilization.
• Sporophyte: a multi-celled diploid (2n) body that grows by mitosis from a zygote, produces spore-bearing structures.
• Spores: resting structures, able to survive harsh conditions, germinate to form gametophytes.
Adaptations to Land
• Root systems
• Shoot systems
• Vascular tissues
• Waxy cuticle for water conservation
Properties of Plants
• Photosynthetic
• Plant cells have a cell wall (cellulose)
• Organs: roots, stems, leaves
• Sessile: non-mobile, stay in one place
• Indeterminate growth
• Life cycle: Gametophyte
Sporophyte
Milestones in Plant Evolution
charophytes bryophytes lycophytes horsetails ferns cycads ginkgos conifers gnetophytes flowering plants
seed plants
plants with true leaves
vascular plants
land plants
(closely related groups)
The Non-Vascular Plants: Bryophytes
• Small, nonvascular, non-woody
• Gametophyte dominates life cycle; has leaf-like, stem-like, and root-like parts
• Usually live in wet habitats
• Flagellated sperm require water to reach eggs
Moss Life Cycle
Fertilization MeiosisDiploid Stage
Haploid Stage
malegametophytetip
femalegametophytetip
Zygote
Development of mature sporophyte (still attached to gametophyte)
Male gametophyte
Female gametophyte
Spores released
Egg
Sperm
Vascular Plants
• Majority of plants
• Have internal tissues that carry water
and solutes (Xylem and Phloem)
• Two groups
– Seedless vascular plants
– Seed-bearing vascular plants
Seedless Vascular Plants
• Like bryophytes:
– Live in wet, humid places
– Require water for fertilization
• Unlike bryophytes:
– Sporophyte is free-living and
has vascular tissues
Rise of Seed-Bearing Plants
• Seeds appeared about 360 million
years ago
• Seed ferns and gymnosperms were
dominant at first
• Angiosperms arose later
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 pollinators
Seeds
• Ovules are female reproductive structures that become seeds
• Consist of:– Female gametophyte with egg cell
– Nutrient-rich tissue (endosperm)
– Jacket of cell layers that will form seed coat
Seed-Bearing Vascular Plants
• Gymnosperms arose first– Conifers– Others…
• Angiosperms arose later– Monocots– Dicots
Special Traits of Seed-Bearing Plants
• Pollen grains– Arise from microspores– Develop into male gametophytes– Can be transported without water
• Seeds– Megaspores inside ovules– Embryo sporophyte inside nutritive tissues
and a protective coat– Can withstand hostile conditions
Gymnosperms
• Plants with “naked seeds”
• Seeds don’t form inside an ovary
• Four groups
Conifers Ginkgos
Cycads Gnetophytes
Conifer Characteristics
• Widest known, largest number of living species
• Woody trees or shrubs
• Most are evergreen
• Bear seeds on exposed cone scales
• Most produce woody cones
Pine Cones
• Woody scales of a “pine cone” are the
parts of where megaspores formed
and developed into female
gametophytes
• Male cones, where microspores and
pollen are produced, are not woody
PineLife
CycleSporophyte(Pine Tree)
Female cone
Male cone
Ovule
Fertilization Meiosis
MicrosporesMegaspores
Pollen sac
Egg View insideovule
Pollen tube
Seed
Angiosperms
• Flowering plants
• Defining feature: Ovules and (after fertilization) seeds are enclosed in an ovary
• Two classes: Monocots and Dicots
Vascular Tissues
Xylem = absorbs water and nutrients up through the roots
- movement only in the upward direction
Phloem = distributes sugars, amino acids, & organic nutrients
- movement is multi-directional
Monocots vs. Dicots
Monocots• 1 cotyledon• Parallel veins• Fibrous root• Flower parts in 3’s• Stem organization:
- Scattered bundles
Dicots• 2 cotyledons• Net-like veins• Tap root• Flower parts in 4’s / 5’s• Stem organization:
- Bundles in a ring
A Fungus is Not a Plant
There are many significant differences between fungi and plants, including
– fungi are hetertrophs
– fungi have filamentous bodies (Hyphae, Mycelium)
– fungi have nonmotile sperm
– fungi have cell walls made of chitin
– fungi have nuclear mitosis