Plants and the Littoral Zone
Ecology and Diversity
Growth Habits and Locations of Plant
Types in the Littoral Zone
Emergent Macrophytes
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Rooted in the substrate
Leaves fully exposed to air
Usually rhizomatous
Stems and leaves usually with aerenchyma or
lacunae
• Nutrient uptake from the sediment and
inorganic carbon from the air
Examples of emergent macrophytes
• Typha: commonly
called cattail, is very
characteristic of
wetland
communities. Typha
is a monocot related
to grasses.
Examples of emergent macrophytes
• Glyceria:
mannagrass, is an
aquatic grass with
leaves that are very
rough to the touch
Examples of emergent macrophytes
• Phragmites: called
common reed, is a
grass that grows
aggressively in
aquatic and semiaquatic
environments
Examples of emergent macrophytes
• Zizania: wild rice, is
related to the grass,
Oryza, true rice
Examples of emergent macrophytes
• Eleocharis: spikerush
(more appropriately
spikesedge), is a
grass-like plant in the
sedge family. The
genus is similar to a
diminuitive Scirpus in
that it makes spikelike stems without
leaves.
Examples of emergent macrophytes
• Scirpus: commonly
called bulrushes, are
in the sedge family.
They are rhizomatous
with hollow stems.
Leaves are associated
with the
inflorescence, which is
subapical.
Examples of emergent macrophytes
• Carex: the
dominant genus
of sedges (>1500
species). These
grass-like plants
have stems that
are triangular in
x-section.
Examples of emergent macrophytes
• Juncus: rush,
superficially
resembles
Eleocharis.
However, it
forms a tuft of
spike-like
stems that
grow from a
basal rosette
of leaves.
Examples of emergent macrophytes
• Polygonum: smartweed
or knotweed, is
recognized by having
swollen nodes and has
many species, but only
a few are aquatic. The
native species is
frequently found
associated with the
margins of lakes,
ponds, reservoirs, and
in backwater areas of
rivers and creeks.
Japanese Knotweed, an
invasive from Asia, also
is found associated
with wet areas, but
rarely in the water.
Examples of emergent macrophytes
• Equisetum: horsetail.
The common one
found in water is E.
fluviatile, the river
horsetail. These
plants are related to
ferns.
Floating-leaved rooted macrophytes
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Generally rhizomatous
Floating leaves with cuticle on upper surface
Petiole usually very long
Nutrient uptake from the sediments and
inorganic carbon often from both the water
and air
Floating-leaved macrophytes, rooted
• Nuphar: spatterdock
or cow lily, is
rhizomatous with
large floating leaves.
All stems and roots
are in the mud. The
plant is common to
aquatic systems
throughout the
northern hemisphere.
Floating-leaved macrophytes, rooted
• Nymphaea:
waterlily is very
similar to Nuphar
but it has a large
showy flower, which
makes it a favorite
of water gardens.
Floating-leaved macrophytes, rooted
• Brasenia: watershield
is similar to Nuphar,
but smaller. The
stems, though
technically
rhizomatous, emerge
from the substrate.
Floating-leaved macrophytes, rooted
• Nelumbo, lotus,
resembles
Nymphaea.
However, some
of its leaves are
emergent. One
species is native
to North
America.
Floating-leaved macrophytes, rooted
• Potamogeton:
pondweed is rooted
with elongate stems
and floating leaves.
Unrooted floating-leaved macrophytes
• Many have gas-filled floats or tissue
• Some have leaves that are entirely aerial
• All have a hanging root system (or modified
tissues that operate as roots), thus nutrient
uptake entirely from water but inorganic
carbon from the air
• Stems are highly reduced
Floating-leaved macrophytes, not rooted
• Lemna: duck weed,
a common floating
plant throughout
the northern
hemisphere.
Floating-leaved macrophytes, not rooted
• Wolffia, water meal,
is the world’s
smallest flowering
plant. Often, it is
found together with
Lemna.
Floating-leaved macrophytes, not rooted
• Eichhornia, water
hyacinth is a large
free-floating plant
from South
America that has
become a noxious
weed of waterways
in the southern US.
Floating-leaved macrophytes, not rooted
• Pistia, water lettuce,
was first found in
Egypt near the Nile.
Now it has been
dispersed by humans
to nearly all tropical
and subtropical
waterways. It has
become a pest in the
US on some
waterways.
Free-floating unrooted macrophytes
• Plants are almost entirely submerged, but may
float at the surface
• In general, the leaves are highly-dissected
• Fragmentation a major form of reproduction
and dispersal
• Roots rare; thus, nutrient uptake entirely from
water
Free-floating macrophytes, not rooted
• Utricularia:
bladderwort, is an
aquatic carnivorous
plant. There are more
than 250 species and
the genus has global
distribution. Some
species have become
pests in some regions.
Free-floating macrophytes, not rooted
• Ceratophyllum,
hornwort or coontail,
is global in
distribution and
usually found in hard
water ponds and
lakes.
Submerged rooted aquatic plants
• In general, the leaves are highly dissected
• Nutrient uptake both from water and
sediment
Submerged rooted macrophytes
• Myriophyllum,
water milfoil, is
native to Eurasia
and has become a
pest in many
relatively still
bodies of water.
Submerged rooted macrophytes
• Elodea: waterweed
is submerged and
native to North
America. It can root
in sluggish streams.
They can be very
abundant in
nutrient-rich lakes
and ponds. Used
globally as an
aquarium plant.
Submerged rooted macrophytes
• Vallisneria: water
celery or tape
grass, is a rooted
plant with broad
leaves that is
frequently found
in local creeks.
Submerged rooted macrophytes
• Isoetes, quillwort is
a fern ally with
corm-like bases to
the leaves. An
indicator of acidsensitive water.
Sometimes they are
emergent.
Submerged rooted macrophytes
• Chara, muskgrass
or skunkweed, is a
non-vascular
plant. Many of
the species have a
fetid odor. This
genus usually is
found in hard
water ponds and
lakes.
Submerged rooted macrophytes
• Nitella, stoneworts or
brittleworts, are
related to Chara but
may occur in soft
water ponds and
lakes. They do not
deposit calcium
carbonate in their
cell walls as many
Chara species do,
and therefore, are
soft to the touch.
Zonation in Ozera Nero
• From the shore to
the lake center
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–
–
Salix
Phragmites
Typha
Scirpus
Equisetum
Potamogeton
Nuphar
Lemna (in all
emergent plants)
– Ceratophyllum
Sam Rayburn Reservoir
• Marginal
macrophytes make
tight concentric
bands of:
– Nitella
– Potamogeton
– Elodea
Main Stem of the Susquehanna River
• Beds of
macrophytes in
backwater
areas and in the
clear water of
the West
Branch
– Vallisneria
– Polygonum
– Glyceria
Impacts of macrophyte dominance
• High primary production
• Decreased turbulence
• More efficient (than algae) nutrient uptake
and sequestration??
• Increased water clarity
• High organic load
Heterophylly
• Many aquatic plant
species show differences
in leaf shape when in or
out of the water.
Reproduction, dispersal, and dormancy
• Asexual: e.g. Potamogeton
– Winter buds
– Agamospermy
• Vegetative: e.g. Myriophyllum
• Sexual:
– Insect pollination e.g. Nuphar
– Wind pollination e.g. Typha
– Water pollination e.g. Potamogeton and Elodea
Movement of gases
• Diffusion-dependent
throughflow
convections.
• e.g. Fig 18-2
Movement of gases
• Nonthroughflow
• Venturi-induced throughflow
• Methane to atmosphere very high for
emergent and floating-leaved rooted plants.
• Oxygen transport in submerged macrophytes
• Lacunae in roots and rhizomes may promote
an oxidizing area around the roots which
protects from H2S
Carbon uptake
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CO2 diffusion much slower in water than air
No cuticle in submerged leaves
Chloroplasts in epidermis
Many can decarboxylate bicarbonate
Often high release of CO2 from sediments in
areas with macrophytes
• Can recirculate CO2 within plant via lacunae
CAM Metabolism
• Found in certain aquatic plants and certain
desert plants.
• Allows for CO2 uptake at night when inorganic
carbon highest in water.
CAM
photosynthesis
Keeley, J.E. 1985. The role of
CAM in the carbon economy
of the submerged-aquatic
Isoetes howellii. Verh.
Internat. Verein. Limnol. 22:
2909-2911.
Phosphate and nitrate enrichment
relative to biomass
Plants and Water Velocity
Relationship between pH and alkalinity
RIVERS
RESERVIORS
LAKES
Littoral
zone/wetland
Land-water interface
well developed
Land-water interface
poorly developed
Land-water interface
well developed
Macrophyte
community
structure
With emergent,
floating, and
submerged
macrophytes
Wetland macrophytes
in riverine portion,
limited submerged
plants, floating plants
dominant
Well-developed
emergent, floating,
and submerged
macrophytes
Mainly through roots
Most from sediments
Light acquisition
Limited by canopy in
Limited to shallow
low order streams and areas due to turbidity
by turbidity and algae
in high order streams
Mostly unrestricted
except for submerged
macrophytes
Macrophyte
biomass and
production
High in floodplain; low
in low order streams,
highest in mid-order
streams and low in
high order streams
High to very high,
mainly with emergent
macrophytes
Nutrient acquisition Mainly through roots
Low to moderate,
mainly in riverine
wetlands; floatingleaved macrophytes
can be very
productive