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Kingdom Plantae
• Arose from Green Algae approximately
1 billion years ago
• Red and brown algae are not included
• A single species of freshwater green
algae gave rise to the entire Kingdom
• Green algae subsequently split into two
groups – the Chlorophytes which never
made it to land, and the Charophytes,
the sister group of all land plants
Kingdom Plantae is monophyletic
Kingdom Plantae
• Eukaryotic
• Multi-cellular
• Cell walls are made
of cellulose
• Autotrophic
Kingdom Plantae
• Adaptations for living on land
– Waxy cuticle – secreted onto surface;
impermeable
– Stomata – tiny mouth-shaped openings,
which can be opened and closed
– Gametangia – structures that produce (and
house) gametes
Plant Life Cycles
• Reproduction is accomplished by an
alteration of generations
• A multi-cellular diploid phase alternates
with a multi-cellular haploid phase
• The gametophyte (“gamete plant”) is
haploid; produces gametes by mitosis
• The sporophyte (“spore plant”) is diploid;
formed by two gametes; produces spores
by meiosis, which germinate and develop
into gametophytes!
Plant Life Cycles
• The diploid sporophyte is the dominant
portion of the life cycle in most land plants
(vascular plants: ferns, gymnosperms and
angiosperms)
• However, the haploid gametophyte is the
dominant portion of the life cycle in
Bryophytes (liverworts, hornworts and
mosses)
Plant Life Cycles
• Bryophyte gametophyte
• Vascular plant sporophyte
(sori on the back of a fern)
Plant Life Cycles
• In seed plants, the haploid gametophytes
are male and female; the males occur as
pollen and the females occur as seeds
• The seed growing on the diploid
sporophyte ‘parent’ contains a haploid
female gametophyte bearing an egg cell,
and is fertilized by a pollen grain which
contains a miniature male gametophyte
• diploid zygote diploid sporophyte
Plant Life Cycles
• Pine cones contain seeds and pollen
• The familiar pine cone is the female
• The male (containing pollen) is not really a
cone at all, but rather a cluster
Chlorophytes
• Green Algae
• Aquatic
• Unicellular and multi-cellular
Bryophytes
• The closest living descendents of the first
land plants
• Simple, but highly adapted
• Lack roots
• Mycorrhizal associations are found in
many groups
• Typically small (the conspicuous form are
gametophytes!); <7cm in height
• Non-vascular but have conducting cells for
water and nutrients
Bryophytes
• Liverworts and Hornworts
Bryophytes
• Mosses
– Multi-cellular rhizoids
– Rhizoids function as
roots; anchor to
substrate and absorb
water
– Green parent plant is
the gametophyte;
sporophyte nutritionally
dependent on
gametophyte
Tracheophytes
• The first vascular plants
• Evolved lignified tissues for conducting
water, nutrients and photosynthetic
products through the plant
• Xylem – draws water and nutrients up
from roots to the upper sections of the
plant
• Phloem – conducts photosynthetic
products and hormones throughout plant
• “Xylem up, Phloem down!”
You are Here
Tracheophytes
Tracheophytes (cont.)
Lycophytes and Pterophytes
• The Club Mosses (Lycophytes; not true
mosses) and Ferns (Pterophytes)
Seed Plants
• Seeded plants
• Embryo protected by an extra layer of
sporophytic tissue; during development,
this tissue hardens to produce the seed
coat
• Seed protects embryo from drought,
allows for easier dispersal, and introduces
a dormant stage, that allows the embryo to
survive until environmental conditions are
favorable for growth
Seed dispersal
nationalzoo.si.edu/Anima
lsBackyardBiology/Urban
NatureWatch/Watches/Pl
antAdap...ersal.cfm
http://www.uni-heidelberg.de/institute/fak14/ipmb/phazb/birdsberries.htm
http://www.ise514.org.uk/members/Photos/Plants/seed%20dispersal/fruit%20bat%20on%20%20fig.JPG
www.flickr.com/photos/elancel/3608295338/
Gymnosperms
• Plants with “naked seeds”
Gymnosperms
• Gametophyte stage is further reduced
• Male gametophyte is inside pollen
• Female gametophyte inside seed…
Reminder – conifers are gymnosperms
• Pine cones contain seeds and pollen
• The familiar pine cone is the female
• The male (containing pollen) is not really a
cone at all, but rather a cluster
Angiosperms
• Flowering Plants
• Include Monocots (one cotyledon) and
Dicots (two cotyledon)
Angiosperms
• Flowers – reproductive organs; considered
to be modified stems with modified leaves
• Consist of:
– Stamen - produces pollen, bears pollen on
anther
– Carpel – includes the ovary (the swollen
base), stigma (sticky, pollen grains adhere
to), style (connects the stigma to the ovary)
• Ovary later develops into a fruit
Angiosperms
Angiosperms
• The flower is designed (evolved) to attract
pollinators (or to aid in wind dispersal)
• The flower uses color, scent, morphology and
reward to attract pollinators
– Color – advertises to pollinators
– Scent – attracts pollinators
– Morphology – can be specific, attracts pollinators
(hummingbird bills, bee orchids)
– Reward – nectar; sweet and nutritious
• Flowers that self-fertilize tend to small,
inconspicuous and unscented!
http://www.flickr.com/photos/41019338@N00/2808113879/
Coevolution