Download Moving onto Land Problems and Solutions

Characteristics of All Land Plants
Similarities to Green Algae-Charophytes
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Chlorophyll a & b, carotenoids
Starch storage in plastids
Cellulosic cell walls
Phragmoplast
Flavonoids and phytochrome
Evolution toward large immotile
egg protected by sterile cells
Moving onto Land
Problems and Solutions
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Control desiccation (cuticle)
Protection of gametes and embryos
Transporting water and nutrients
Gamete transportation
– Move away from water transport; need a desiccant
resistant vehicle for sperm transport
Characteristics of All Land Plants
Life Cycle
• Sporic meiosis and
Alternation of Generation
• Gametophytes are haploid
and produce gametes
• Sporophytes are diploid,
and make haploid spores
in sporangia (meiosis)
• Spores grow into
gametophytes
Phylum Bryophyta—Mosses,
Liverworts, and Hornworts
• Primitive land plants
• Photosynthetic-free living gametophye
• Zygote and sporophyte never leave
female gametophyte
• Sporophyte is dependant on
gametophyte for nutrition
• Free-swimming sperm
Mosses-Life Cycle
• Simple, undifferentiated leaves
• No stoma nor guard cells
– Exception to rule (sporophyte &
hornworts)
• Rely on moist environments for
reproduction and plant protection
• Adaptive growth form
Bogs—isolated wetlands. Bogs are carbon sinks. The acidic
condition of bogs is due to Sphagnum moss.
Few decomposers. Why? Cold, low oxygen (anoxic),
and acidic conditions. This allows organic matter (i.e., peat)
to accumulate in bogs.
Sphagnum Moss-Ecological
and Economic Importance
•Peat Products
–Peatcrete
–Peatwood
–Insulation
–Scotch
–Peatmoss
•Living Sphagnum moss
–Sterile dressing
–Absorbent material
–Decoration
Sphagnum moss with
ballistic sporangia—
Sphagnum Ballistics
People of the Bog--Europe
Permit studies of past cultures.
Hyde Park Mastodon
Moose Dung Moss-Splachnum
• Splachnum only grows
on moose dung.
• Sporophyte mimics
flowers and attracts
flies on moose pies.
Moss Gardening--Asia
Liverworts
• Thallus form of liverworts
resembles human live—
”Doctrine of Signatures”
• Thallus with differentiated
tissues—photosynthetic
layer, pores for gas exchange
• Live in moist seepage areas
Gemmae cup
Thallus structure and asexual
Reproduction (gemmae).
Sexual Structures of Liverwort
Gametophytes
Male gametophyte with
antheridiophores
Female gametophyte with
archegoniophores
What’s next?
Building a complex plant adapted to
living all across land.
• Mosses and liverworts are limited to moist,
humid environments
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Lack vascular tissue
Lack cuticle
Undifferentiated leaves, stems, rhizoids
Require water for reproduction
Gametophyte dominated lifestyle
Homospory
Summary Time—Mosses and
Liverworts
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gametophyte dominant lifestyle
ephemeral sporophyte
simple undifferentiated leaves
motile sperm
undifferentiated spores—homospory
need moist, humid habitats for survival