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Plant Diversity
Plant Diversity
Overview
Major Characteristics of Land Plants
Nonvascular Plants
Vascular Plants
Plant Diversity
Major Plant Characteristics
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Alteration of Generations
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Sporangium (sporophyte)
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Gametangium (gametophyte)
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Spore (diploid) forming structure
Gamete (haploid) producing
structure
Apical meristem
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Found in vascular plants
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Produces growth in the roots &
shoots of plants
Plant Diversity
Nonvascular Plants
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Lack vascular tissue
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Seedless
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Include the “Bryophytes”; liverworts, hornworts, & mosses
Plant Diversity
Nonvascular Plants
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“Bryophytes”
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Constitute a small number of
the land plants
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All are seedless
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Lack lignin (a polymer of cell
walls)
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18,000 species
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Mostly inhabit damp habitats
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Small & resistant to drying
Plant Diversity
Nonvascular Plants
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“Bryophytes”
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Liverworts
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~6,000 species
Some produce lobate
(liver-shaped)
gametophytes
Plant Diversity
Nonvascular Plants
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“Bryophytes”
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Hornworts
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~100 species
Short, blue-green
gametophyte
dominates lifecycle
Sporophyte is long,
narrow, & pipe-like and
characterizes the group
00
Plant Diversity
Nonvascular Plants
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“Bryophytes”
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Mosses
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~12,000 species
Rhizoids allow them to anchor to
substrates without digging in
Mosses slow erosion, hold
moisture & nutrients in the soil
Provide shelter to small animals
Provide food to large herbivores
Sensitive to air-borne copper
salts therefore are helpful in
monitoring air quality
Plant Diversity
Vascular Plants
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Possess vascular tissue
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Network of cells that transport water & solutes to the body of the plant
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Seedless & seed-bearing plants
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Include lycophytes, pterophytes, gymnosperms, & antiosperms
Plant Diversity
Vascular Plants
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Vascular Tissue
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Xylem
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Phloem
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Long distance transport of water &
minerals through the plant
Transport sugars, proteins, & other
solutes through the plant
Roots
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Extensive stable filaments
containing much vascular tissue
which
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Absorb water & nutrients from the soil
Serve to anchor the plant
Plant Diversity
Vascular Plants
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Leaves, Sporophylls,
Strobili (Seedless
Vascular Plants)
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Leaves
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Sporophylls
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Improve photosynthesis
Leaves which bear sporangia
Strobili
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Structures containing the
sporangia on the sporophylls
Plant Diversity
Seedless Vascular
Plants
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Club Mosses
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–
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Small stem with
microphylls (small
leaves)
~1,000 species
Require watery
environments for
reproduction
Plant Diversity
Seedless Vascular
Plants
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Horsetails
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–
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Usually in watery
environments like
marshes
Jointed stems
Needle-shaped leaves
extend from whorls off
evenly-spaced rings on
the stems
Plant Diversity
Seedless Vascular
Plants
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Ferns
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–
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~12,000 species
Share characteristics to
seed-bearing vascular
plants
Form large leaves
(fronds) and branching
roots
Plant Diversity
Seed-bearing Vascular
Plants
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Gymnosperms
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Characterized by
● Naked seeds
● Separate male & female
gametes
● Pollination by wind
● Possess tracheids
● Elongated cells in the
xylem which transport
water & solutes in the
vascular system
Include the conifers, cycads,
and ginkgophytes
Plant Diversity
Seed-bearing Vascular
Plants
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Gymnosperms
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Conifers
● Dominate the gymnosperms
● Scale or needle-like leaves
contain a waxy cuticle to
reduce drying
● Dominate high altitides/cold
climes
● Contain tracheids but not
vessel elements = “soft
woods”
● Includes evergreens like
pines, firs, spruce, cedars,
sequoias, and yews
Plant Diversity
Seed-bearing Vascular
Plants
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Gymnosperms
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Cycads
● Prefer mild climes
● Large compound
leaves
● Bear large cones
● May be pollinated
by beetles rather
than wind
Plant Diversity
Seed-bearing Vascular
Plants
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Gymnosperms
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Ginkgophytes
● Only one species
survives, Ginkgo biloba
● Fan-shaped leaves with
vertical venation
● Resistant to pollination
since male & female
organs are on separate
plants
● Female plant produces
seeds that smell like
rancid butter
Plant Diversity
Seed-bearing Vascular
Plants
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Angiosperms
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Flowering plants
Dominate terrestrial
ecosystems
>260,000 species
Produce flowers & fruits
Plant Diversity
Seed-bearing Vascular
Plants
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Angiosperms
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Flowers are modified
leaves that attract
pollinators
Plant Diversity
Seed-bearing Vascular
Plants
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Angiosperms
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Male flower parts
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Stamen-surround
carpel
Filament-support
anther
Anther-pollen maker
Plant Diversity
Seed-bearing Vascular
Plants
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Angiosperms
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Female flower parts
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Carpel or Pistil
Style-long thin tube of the
carpel leading to the stigma
Stigma-sticky structure for
collecting pollen
Ovary-contains ovules which
become seeds upon
fertilization
Plant Diversity
Seed-bearing Vascular Plants
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Angiosperms Life cycle
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Microspores develop into pollen grains,
which are the male gametophytes, while
megaspores form an ovule that contains
the female gametophytes.
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In the ovule, the megasporocyte undergoes
meiosis, generating four megaspores; three
small and one large; only the large
megaspore survives and produces the
female gametophyte (embryo sac).
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When the pollen grain reaches the stigma,
it extends its pollen tube to enter the ovule
and deposits two sperm cells in the embryo
sac.
Source: Boundless. “The Life Cycle of an Angiosperm.” Boundless Biology. Boundless, 20 Sep. 2016. Retrieved 24 Nov. 2016 from
https://www.boundless.com/biology/textbooks/boundless-biology-textbook/seed-plants-26/angiosperms-160/the-life-cycle-of-anangiosperm-626-11847/
Plant Diversity
Seed-bearing Vascular Plants
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Angiosperms Life cycle
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The two available sperm cells allow for
double fertilization to occur, which
results in a diploid zygote (the future
embryo) and a triploid cell (the future
endosperm), which acts as a food store.
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Some species are hermaphroditic
(stamens and pistils are contained on a
single flower), some species are
monoecious (stamens and pistils occur
on separate flowers, but the same
plant), and some are dioecious
(staminate and pistillate flowers occur on
separate plants).
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Source: Boundless. “The Life Cycle of an Angiosperm.” Boundless Biology. Boundless, 20 Sep. 2016. Retrieved 24 Nov.
2016 from https://www.boundless.com/biology/textbooks/boundless-biology-textbook/seed-plants-26/angiosperms160/the-life-cycle-of-an-angiosperm-626-11847/
Plant Diversity
Seed-bearing Vascular
Plants
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Angiosperms Life cycle
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The resulting zygote (fertilized
ovule) develops into an embryo
containing one or two leaf-like
organs called cotyledons
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Monocots
● Seed plants that develop one
cotyledon
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Dicots
● Seed plants that develop two
cotyledons