Transcript Prairie Grasses - Blue Valley Schools

Prairie
Factors Maintaining Prairie
1.
2.
3.
•
Low Rainfall
Fire
Grazing
Each of these factors inhibits the
growth of woody plants (trees and
such) while favoring the growth of
grasses and other herbaceous plants
Grasses in a Grassland
• Grass (Family Poaceae) are monocots and
compose between 60% and 80% of plant
species in a mature prairie habitats
• The three most common prairie grasses are:
1) Big Bluestem – Andropogon gerardi
2) Indian Grass – Sorghastrum nutans
3) Little Bluestem – Andropogon scoparius
Fire & Growth
Grass Adaptations: Moisture
• They reduce their surface area by having narrow leaf
blades with parallel veins that allow the leaf to curl
further reducing surface area in harsh weather
• They prevent excessive water loss by having a waxy
cuticle covering the leaves, hairy stems reducing
wind and evaporation from the surface, small
recessed stomata, and the C4 photosynthetic
pathway
• They are also known for having roots that make up at
least ½ of the plant that may reach 6 or more feet into
the soil
Grass Adaptations:
Fire & Grazing
• The growth tissue in a grass (meristem) is
located below ground and is able to generate
new tissue after being burnt or eaten
• They take in and store silica (sand) in their
tissue in and effort to wear down the teeth of
grazers
• Their seeds are stimulated to germinate by
chemical produced from burning
Grass Adaptations: Other
• They do not rely on animal pollinators to
mediate sexual reproduction. Instead their
pollen is transported by the wind, a reliable
component of the prairie
• They often reproduce through asexual
means, by modified stem called stolons or
roots called rhizomes that radiate, touch the
ground, and grow into a new plant
I think the prairies will die without grass
finding a voice. Its democracy may be
against it. Prairie grass never seems to
know anybody.
William A. Quayle (1905) The Prairie & The Sea
Compared to trees, shrubs, or forbs,
grasses seem unfathomably plain.
They fail to inspire interest or stir the
imagination. We look at prairie and we
see a great emptiness, a void that
staggers the psyche and leaves much
too much for the mind to wonder.
Randy Winter (1987) Nature Notes
Every American has the right as part of
his cultural heritage to stand in grass as
high as his head in order to feel some
small measure of history coursing his
veins and personally establish an
aesthetic bond with the past.
William E. Elder (1961) Needs & Problems of Grassland
Presentation
Grass is the most widely distributed of all
vegetable beings and is at once the
type of our life and the emblem of our
mortality…the carpet of the infant
becomes the blanket of the dead.
John J. Ingalls (1872) In Praise of Blue Grass
Grasses are the greatest single source of
wealth in the world.
Agnes Chase (1959) 1st Book of Grasses
The basis of human proliferation is not our
own seed but the seed of grasses.
Evan Eisenberg (1989) Back to Eden
What a thousand acres of compass plant
looked like when they tickled the bellies
of the buffalo is a question never again
to be answered, and perhaps not even
asked.
Aldo Leopold (1949) A Sand County Almanac
Grass Roots & Stems
1. Roots
Fibrous and good as
binding the soil
2. Stems
Flowering stems or
“Culms” are jointed with
hollow internodes. A
“Prophyllum” or modified
first leaf of a branch that
clasps the main culm, may
support branching culms
Grass Leaves
Grass leaves have
parallel-veined blades that
are usually narrow. A
“Foliage” leaf has a
“Sheath” that surrounds
the culm, a “Ligule” that
stands up at the junction
of the sheath and blade,
and the leaf “Blade” itself
Grass Flowers
Grass flower clusters
or inflorescences bear
Scaly units called
spikelets that are
arranged as a:
1.
2.
3.
4.
Spike
Panicle
Spikelike
Raceme