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12 Household Detergents Causing Eutrophication in Freshwater Ecosystems
12.2.2 Botanical Description of Selected Plants
(Pandey 1997)
12.2.2.1 Lemna minor (L.)
Habit They are the smallest and least differentiated angiosperms of the world. They are aquatic in nature and found
floating in fresh waters.
Diversity and distribution The species of Lemna are
widely distributed in both temperate and tropical parts of the
globe except in arctic regions.
Plant morphology The plant body consists of green dorsiventral scale like shoots. The shoots of Lemna range from
1/8 to 3/4 in. The plants do not possess leaves and flat green
shoot perform the functions of leaf. The plant body may
easily be differentiated into a basal portion with two lateral
pockets from which the branches arise. From the ventral surface of the flattened stem a single adventitious root come
out. The apex of root is converted by a few layered sheaths
(root cap) which is visible to the unaided eyes.
The internal structure of the shoot is spongy in nature
and consists of parenchymatous cells. These cells remain
separated from each other by large or small air spaces, which
communicate with the outside by stomata on the upper surface. Vascular tissue is represented by a single median vascular bundle of very simple structure.
Inflorescence In temperate zones, the flowers are rarely
developed. The inflorescence is quite simple and arises in
the pocket.
Flowers The flowers are unisexual. The plants are monoecious, i.e., both male and female flowers develop in the same
inflorescence. The flowers are without perianth (naked). The
male flower consists of single stamen. The filament is stout
bearing at its apex a pair of dithicous anther-halves. The pollen grains are spherical and covered with small warty outgrowths. The female flower consists of single carpel. The
pistil is flask shaped with a short funnel-shaped stigma. The
ovary is unilocular with one to six basal, erect, orthotropous,
or more or less completely anatropous ovules.
Fruit Inconspicuous, usually one seeded.
Seed The seed possess a thick fleshy outer and a thin inner
coat. The embryo consists of a large cotyledon surrounded
by scanty endosperm.
Pollination The pollination is affected by wind, water, or
animals.
Propagation New plant buds arise from the pockets on
either side of the parent plant and eventually break apart.
Over winters as winter buds on the lake bottom, but rarely
reproduces from seeds. A plant can reproduce itself about
every 3rd day under ideal conditions in nutrient rich waters.
Importance of plant Food for fish and waterfowl and
habitat for aquatic invertebrates. Because of its high nutritive value, duckweeds have been used for cattle and pig feed
in Africa, India, and southwest Asia. They are also used to
remove nutrients from sewage effluents.
12.2.2.2 Spirodela polyrrhiza (L.) Shield
Habit They are the smallest and least differentiated angiosperms of the world. They are aquatic in nature and found
floating in fresh waters.
Diversity and distribution The species of Spirodela are
widely distributed in both temperate and tropical parts of the
globe except in arctic regions.
Plant morphology The plant body consists of green dorsiventral scale-like shoots. There are no leaves and flat green
shoot perform the functions of leaf. The plant body (thallus)
is actually an expended “stem” which functions as leaf. It is
oval to oblong, has 5–12 distinct veins and is 4–10-mm long.
The thallus is glossy green and smooth on the upper surface
and reddish purple below. Clusters of 4–16 slender fibrous
roots hang below the surface of the water from each plant.
Each roots ends with a pointed root cap.
The internal structure of the shoot is spongy in nature
and consists of parenchymatous cells. These cells remain
separated from each other by large or small air spaces, which
communicate with the outside by stomata on the upper surface. Vascular tissue is represented by a single median vascular bundle of very simple structure.
Inflorescence In temperate zones, the flowers are rarely
developed. The inflorescence is quite simple and arises in
the pocket.
Flowers The flowers are unisexual. The plants are monoecious, i.e., both male and female flowers develop in the same
inflorescence. The flowers are without perianth (naked). The
male flower consists of single stamen. The filament is stout
bearing at its apex a pair of dithicous anther-halves. The pollen grains are spherical and covered with small warty outgrowths. The female flower consists of single carpel. The
pistil is flask shaped with a short funnel-shaped stigma. The
ovary is unilocular with one to six basal, erect, orthotropous,
or more or less completely anatropous ovules.
12 Household Detergents Causing Eutrophication in Freshwater Ecosystems
12.2.2 Botanical Description of Selected Plants
(Pandey 1997)
12.2.2.1 Lemna minor (L.)
Habit They are the smallest and least differentiated angiosperms of the world. They are aquatic in nature and found
floating in fresh waters.
Diversity and distribution The species of Lemna are
widely distributed in both temperate and tropical parts of the
globe except in arctic regions.
Plant morphology The plant body consists of green dorsiventral scale like shoots. The shoots of Lemna range from
1/8 to 3/4 in. The plants do not possess leaves and flat green
shoot perform the functions of leaf. The plant body may
easily be differentiated into a basal portion with two lateral
pockets from which the branches arise. From the ventral surface of the flattened stem a single adventitious root come
out. The apex of root is converted by a few layered sheaths
(root cap) which is visible to the unaided eyes.
The internal structure of the shoot is spongy in nature
and consists of parenchymatous cells. These cells remain
separated from each other by large or small air spaces, which
communicate with the outside by stomata on the upper surface. Vascular tissue is represented by a single median vascular bundle of very simple structure.
Inflorescence In temperate zones, the flowers are rarely
developed. The inflorescence is quite simple and arises in
the pocket.
Flowers The flowers are unisexual. The plants are monoecious, i.e., both male and female flowers develop in the same
inflorescence. The flowers are without perianth (naked). The
male flower consists of single stamen. The filament is stout
bearing at its apex a pair of dithicous anther-halves. The pollen grains are spherical and covered with small warty outgrowths. The female flower consists of single carpel. The
pistil is flask shaped with a short funnel-shaped stigma. The
ovary is unilocular with one to six basal, erect, orthotropous,
or more or less completely anatropous ovules.
Fruit Inconspicuous, usually one seeded.
Seed The seed possess a thick fleshy outer and a thin inner
coat. The embryo consists of a large cotyledon surrounded
by scanty endosperm.
Pollination The pollination is affected by wind, water, or
animals.
Propagation New plant buds arise from the pockets on
either side of the parent plant and eventually break apart.
Over winters as winter buds on the lake bottom, but rarely
reproduces from seeds. A plant can reproduce itself about
every 3rd day under ideal conditions in nutrient rich waters.
Importance of plant Food for fish and waterfowl and
habitat for aquatic invertebrates. Because of its high nutritive value, duckweeds have been used for cattle and pig feed
in Africa, India, and southwest Asia. They are also used to
remove nutrients from sewage effluents.
12.2.2.2 Spirodela polyrrhiza (L.) Shield
Habit They are the smallest and least differentiated angiosperms of the world. They are aquatic in nature and found
floating in fresh waters.
Diversity and distribution The species of Spirodela are
widely distributed in both temperate and tropical parts of the
globe except in arctic regions.
Plant morphology The plant body consists of green dorsiventral scale-like shoots. There are no leaves and flat green
shoot perform the functions of leaf. The plant body (thallus)
is actually an expended “stem” which functions as leaf. It is
oval to oblong, has 5–12 distinct veins and is 4–10-mm long.
The thallus is glossy green and smooth on the upper surface
and reddish purple below. Clusters of 4–16 slender fibrous
roots hang below the surface of the water from each plant.
Each roots ends with a pointed root cap.
The internal structure of the shoot is spongy in nature
and consists of parenchymatous cells. These cells remain
separated from each other by large or small air spaces, which
communicate with the outside by stomata on the upper surface. Vascular tissue is represented by a single median vascular bundle of very simple structure.
Inflorescence In temperate zones, the flowers are rarely
developed. The inflorescence is quite simple and arises in
the pocket.
Flowers The flowers are unisexual. The plants are monoecious, i.e., both male and female flowers develop in the same
inflorescence. The flowers are without perianth (naked). The
male flower consists of single stamen. The filament is stout
bearing at its apex a pair of dithicous anther-halves. The pollen grains are spherical and covered with small warty outgrowths. The female flower consists of single carpel. The
pistil is flask shaped with a short funnel-shaped stigma. The
ovary is unilocular with one to six basal, erect, orthotropous,
or more or less completely anatropous ovules.