Transcript What is a plant?

What is a plant?
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Multicellular
Eukaryotic cell
With cell wall of cellulose
Waxy, protective coating called cuticle
Usually contains chlorophyll for its role as
an autotroph (photosynthesis)
Plant Structures
External plant structures such as leaves, stems, roots,
flowers, fruits, and seeds are known as plant organs.
Each organ is an organized group of tissues that works
together to perform a specific function. These structures
can be divided into two groups: sexual reproductive and
vegetative. Sexual reproductive parts produce seed; they
include flower buds, flowers, fruit, and seeds. Vegetative
parts include roots, stems, shoot buds, and leaves; they
are not directly involved in sexual reproduction.
Vegetative parts often are used in asexual forms of
reproduction such as cuttings, budding, or grafting.
Alternation of Generations
Reproduction in Plants
For growth
Forms a Zygote
e.g., Eggs/Sperm
Archegonia/Antheridia
For growth
Sporophyte
• “spore plant”
• Diploid state
• Many common plants
have this as their
dominant form
Sporangium
• Specialized organ
• Diploid cells
• Produces hapliod
spores to release to the
environment
Meiosis in Sporangium
• Reduction division
• Starts with diploid
number, finishes with
haploid number in the
new cells (spores)
Spore
• Haploid asexual
reproductive cell
• Released into the
environment
Mitosis
• Growth of cell by
replication of heredity
and cell division into a
multi-cellular
organism
Gametophyte
• “gamete plant”
• Produces gametes (sex
cells) for sexual
reproduction
• Eggs from archegonia
• Sperm from the
antheridia
Fertilization
• Sperm nucleus unites
with egg nucleus deep
in the ovary of the
plant
Mitosis
• Growth of cell by
replication of heredity
and cell division into a
multi-cellular
organism
This multicellular organism is the next
generation of sporophyte…..you are
back to square one!
For growth
Forms a Zygote
e.g., Eggs/Sperm
Archegonia/Antheridia
For growth
Plant Phylogeny
• Bryophyta – nonvascular, non-seed plants
like mosses and liverworts
• Psilophyta – non-seed vascular plants like
tropical/subtropical whisk ferns
• Lycophyta – non-seed vascular plants like
club mosses
• Sphenophyta – non-seed vascular plants like
horsetails
Plant Phylogeny (cont.)
• Pterophyta – non-seed vascular plants like
the ferns
• Cycadophyta – vascular seed plants like the
palm-like cycads
• Gnetophyta – unusual, distinctive vascular
seed plants like Welwitschia
• Ginkgophyta – very rare vascular seed tree
with fan-shaped leaves (1 species)
Plant Phylogeny (cont.)
• Coniferophyta – cone-bearing vascular seed
plants like pine trees
• Anthophyta – flowering vascular seed
plants like roses (dicots) and lilies
(monocots)
Bryophyta
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Non-vascular, so…….
Live in moist sheltered places
Non-seed
Mosses, hornworts, and liverworts
Plant life cycle needs water for sperm
Vegetative reproduction also
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1 = sporophyte
2 = gametophyte
3 = sporangium case
4 = stalk
Ferns and their allies
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Vascular plants (major advancement)
need water for reproduction
Seedless
Alternation of Generations
Ferns, club moss, horsetails
The beginnings of true organs
Roots to anchor, absorb water
and minerals, and store food
Leaves for photosynthesis and
storage of food
Stems for support, storage, and
transport of water up and food
down
(Flowers for reproduction,
yielding the fruit in seed plants)
Sporophyte
Gametophyte with young
sporophyte
Seed Plants
• Vascular
• Produce seeds (major advancement)
• Gymnosperms (bear seeds naked on bracts
of cones) and Angiosperms (flowering
plants with seeds in tissues)
• Free of water because male gametophyte is
in pollen grain carried by wind, water,
insects, or small animals
Gymnosperms
• Cone bearers
• Gnetophytes, cycads, gingkoes, conifers
• Alternation of Generations
“Naked Seeds”
Seeds lying uncovered on the bract
Alternation of Generations
Angiosperms (Phylum Anthophyta)
• Flowering plants
• Vascular seed plants
• Fruits with seeds
– Dry fruits
– Fleshy fruits
• Most of the commons plants we know
• Alternation of Generations
Alternation of Generations
The Typical Flower (reproductive
organ)
A comparison of Classes
Dicotyledonae vs Monocotyledonae
XYLEM AND PHLOEM
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XYLEM = “water UP”
PHLOEM = “food DOWN”
HERBACEOUS STEM - GREEN
VASCULAR BUNDLES
WOODY TREE
Plant Life Spans
• Annual – germinate, grow, flower, seed, and
die in one growing season
• Biennial – germinate, grow, develop first
season; flower, seed, and die second season
• Perennial – live and flower (seed) for many
seasons