Nonvascular Plants

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Transcript Nonvascular Plants

Nonvascular Plants
CH. 29.2 – DEC 3, 2014
NONVASCULAR PLANTS
 Nonvascular plants lack vascular tissue
 Have a “leafy” appearance but do not have true
roots, stems and leaves

Only have rootlike, stemlike, leaflike structures
NONVASCULAR PLANTS
 Gametophyte is the dominant generation in
nonvascular plants

i.e. the generation that we recognize as the plant

Flagellate sperm swim in a continuous film of water to the vicinity of the
egg

Sporophyte develops from the zygote, is attached to and derives its
nourishment from the gametophyte shoot
Bryophytes
 Life cycles of mosses and other bryophytes are
dominated by the gametophyte stage
 Bryophytes are represented today by three phyla of small
herbaceous (nonwoody) plants


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Liverworts, phylum Hepaticophyta
Mosses, phylum Bryophyta
Hornworts, phylum Anthocerophyta
Bryophytes
Gametophore of
female gametophyte
LIVERWORTS (PHYLUM HEPATOPHYTA)
Plagiochila
deltoidea,
a “leafy”
liverwort
Foot
Seta
Marchantia sporophyte (LM)
HORNWORTS (PHYLUM ANTHOCEROPHYTA)
An Anthoceros
hornwort species
Sporophyte
Sporangium
500 µm
Marchantia polymorpha,
a “thalloid” liverwort
MOSSES (PHYLUM BRYOPHYTA)
Polytrichum commune,
hairy-cap moss
Sporophyte
Gametophyte
Gametophyte
Liverworts
 Have no true roots or shoots
 Require water to reproduce
 Have no or very little leaf structure
 Cannot live in sporophyte form
 Exists in two types
 Flat, lobed thallus (body)
 Leafy (are more numerous)
Liverworts
 Marchantia
 Smooth upper surface
 Lower uracea has numerous rhizoids (rootlike hairs - project into the soil)
 Reproduces both asexually and sexually

Gemmae cups on the upper surface of the thallus contain gemmae

Gemmae = group of cells that detach from the thallus and can asexually start a
new plant
Liverworts
 Sexual reproduction depends on:
 Dish-headed stalks that bear antheridia (flagellated sperm are produced)
 Umbrella-headed stalks that bear archegonia (eggs are produced)
 Following fertilization, tiny sporophytes composed of a foot, short
stalk and a capsule begin growing within archegonia
 Windblown spores are produced within the capsule
Mosses
 Land plant
 Most have no vascular tissue
 Majority of life spent in
gametophyte
 Need water to breed
 No leaves or roots
 Sporophytes are capsules on
stalks
Mosses
 Most reproduced asexually by fragmentation
 Gametophyte of mosses have two stages
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First, there are algalike protonema (branching filament of cells)
After three days of favorable growing conditions, upright leafy thalli
appear at intervals along the protonema.
Mosses

Rhizoids anchor the thalli, which bear antheridia and archegonia

Antheridium – consists of a short stalk, an outer layer of sterile
cells and an inner mass of cells that become the flagellated sperm

Archegonium - which looks like a vase with a long neck, has a
single egg located inside its base
Mosses
 Dependent sporophyte consists of a:
 foot (grows down into the gametophyte tissue)
 stalk
 upper capsule, or sporangium (windblown spores are produced)
 At first, sporophyte is green and photosynthetic
 At maturity it is brown and nonphotosynthetic
 WHY?
 Gametophyte is the dominant generation
 It seems consistent for spores to be dispersal agents
Mosses
Hornworts
 Free-floating aquatic plant, or
land plant
 No vascular tissue
 No true leaves or roots
 Can live in both gametophyte
and sporophyte forms
Adaptations and uses of Nonvascular Plants
 Mosses
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Better at living on walls, fences and even in the shady cracks of hot,
exposed rocks
For these microhabitats, being small and simple seems to be a
selective advantage
 Colonizing bare rock = help convert rocks to soil that can
be used for the growth of other organisms
Adaptations and uses of Nonvascular Plants
 Bogs - ground is wet and acidic
 Dead mosses, especially Sphagnum, do not decay

Accumulated moss called peat or bog moss
Commercially important
 Can be used as fuel
 Nonliving cells can absorb moisture
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 Complete “Check Your Progress”
 pg. 606 #1-2
 Handout