Transcript intro to plants

Plant Characteristics
and Functions
14.1 Classifying Plants
Evolutionary History
 probable that
vascular and nonvascular plants have
common ancestors
with one group of the
plant-like protists, the
green algae
 Celery
 Hornwort
What they have in
common with protists
 both plants and algae use starch as their
primary food resource, they have cellulose
in their cell walls, and they use chlorophylls
a and b during photosynthesis
Differences
 Protists, which can be unicellular or multicellular
organisms, have no roots, stems, or leaves.
 Algae do not need to develop sophisticated systems to
transport nutrients and water because they live in a
medium of water and dissolved nutrients.
 The algae absorb nutrients and water directly from the
external environment, and the material diffuses from
one cell to another.
 There are no specialized cells to move materials within
the organism.
Differences
 members of the plant kingdom live in terrestrial
environments, from wetlands to deserts and from
tundra to tropical rain forests.
 They have adapted many ways to survive these
environments, such as protecting their
reproductive cells and having more sophisticated
ways of transporting material both to and from
their environment and within the plant.
Non-vascular Plants
 i.e. mosses, liverworts, and
hornworts require a moist
environment for two reasons.
 1. they cannot reproduce
unless a film of moisture is
available to carry gametes
between plants
 2. they lack vascular tissue.
They have no system of
tubes to carry water and
dissolved substances
through the plant.
Non-vascular Plants
 some appear to have root-like, stem-like, and
leaf-like parts or structures but they do not
contain vascular tissue. Meaning
 1. root-like structures anchor the plant but do
not absorb water for other parts.
 2. stem-like structures hold the leaf-like parts
up to the light, but they cannot transport food
or water.
 3. Leaflike structures carry out photosynthesis
and make food, but the dissolved food must
diffuse to the other parts of the plant.
Non-vascular Plants
 Because diffusion is generally a slow
process and they have no vascular
tissue, non-vascular plants are restricted
in size.
Uses of non-vascular
plants
 play only a minor role in
providing food or other
materials for people.
 Sphagnum moss is used as a
base for flower arrangements,
used as a source of organic
material for potting and
gardening soils
 countries such as Ireland,
“mined” and cut into blocks as
fuel.
 The princess pine, despite its
name, is a non-vascular plant
that is used in winter flower
arrangements.
FUEL:http://www.talktalk.co.
uk/reference/encyclopaedia/h
utchinson/m0015045.html
Vascular Plants
 vascular tissue to
transport materials within
the plant.
 Extinct: Audrey II
 Not extinct: Fern
Gymnosperm or Angiosperm?
 All trees living today are either one
or the other
 The “sperm” ending indicates that
both groups grow from seed.
 A seed is a complex multicellular
structure that contains an embryo
and a food supply
 The embryo includes an immature
root, an immature shoot, and one
or two “seed leaves” or cotyledons.
 Inside the seed, the food supply
consists of nutritive tissue made up
of starch, oils, and other molecules
needed for development of the
embryo.
Gymnosperms
 gymnosperms have
seeds without a seed
coat and are
attached to the
scales of cones.
 gymnosperms have
seeds without a seed
coat and are
attached to the
scales of cones.
Gymnosperms
 Many gymnosperms, such as conifers, are
adapted to thrive in environments with long cold
winters and low amounts of nutrients in the soil.
 Gymnosperms dominate in large parts of Canada,
northern Europe, and northern Asia.
 The boreal forest, which is characterized by
conifers, is the largest biome in Canada. In
addition, gymnosperms are vital to Canada’s
 economy.
 Gymnosperms provides fibre for making paper and
wood for building materials.
Angiosperms
 The total number of angiosperm
species is far greater than the total
number of gymnosperm species.
 Angiosperms as a group are more
diverse in structure than
gymnosperms. As well,
angiosperms are so widely
distributed around the world that
their total biomass exceeds that of
gymnosperms. Thus, angiosperms
dominate many parts of the
biosphere and they are important
as a source of food for many
organisms, including humans.
Angiosperms







Angiosperms are also known as flowering
plants. Flowers are the angiosperm’s
reproductive organs, which mature into a
seed-containing fruit. The extra protection
of the surrounding fruit gives angiosperm
seeds a strong adaptive advantage over
gymnosperm seeds, which lack an
enclosing fruit.
Once gymnosperm seeds fall or are blown
out of their cones, they have only a thin
cover to protect them.
the fruits of angiosperms are adapted to
facilitate seed dispersal. Some fruits are
tasty (like apples), and the seeds are
dispersed when the fruit is eaten.
Some are sticky (like burrs) and are
dispersed in the feathers or fur of animals.
Others are shaped for flight, such as maple
keys, and are dispersed by the wind.
The group of plants we call angiosperms
includes trees, grasses, vegetables,
wildflowers, and herbs.
All angiosperms produce fruits, many of
which are edible. In addition, the roots,
leaves, and stems of many angiosperms
provide food for humans and other
animals.
Angiosperms: Monocots
and Dicots
 The number of angiosperm
species is so large that biologists
needed a way to group them for
study purposes.
 They found that all angiosperm
seeds have either one or two
(never more) embryonic seed
leaves, or cotyledons, inside the
seed, and agreed to use this
difference as a basis for
classification.
 The two major angiosperm
classes are the monocots, which
have one cotyledon, and the
dicots, which have two cotyledons.
Monocots
 About 10% of all monocots have
woody (tough and rigid) stems.
Examples of woody monocots
include palms and bamboos.
 grown for ornamental purposes in
Canada, but only where the climate
is mild.
 Most woody monocots grow in
warmer climates and are sources of
food such as dates, coconuts,
bananas, palm oil, and sugar.
 Sugar cane, a woody monocot, is a
type of grass.
 Few monocots are suitable to use
as building materials. However, the
hollow stems of bamboo can be
used for buidling
 Bamboo shoots are used as food
by humans and by giant pandas
Monocots as food




Two monocots, bananas and their near relatives, plantains, are a major
source of carbohydrates for many of the world’s people.
During the 1980s, agronomists feared that a fungal infection would wipe
out these important food plants.
They were able to develop a new disease-resistant banana variety.
This proved to be much more difficult than developing a new wheat
variety, for instance, because cultivated bananas and plantains do not
contain seeds. Why do you think this is so?
Our bananas are clonal
 http://www.askabiologist.org.uk/answers/viewtopic.php?id=123
 “Sometimes you can see very tiny dot-like seeds near
the centre of the banana, but they are infertile. The
reason for this, is that edible (the non cooking variety)
are clonal, and to the best of my knowledge, all the
bananas eaten in the 'West' are the 'Cavedish
variety'. Being clonal the genetics of one banana plant
and another is the same, and this means that they are
susceptible to diseases, and in the past cultivated
bananas have been destroyed by bilght. This has the
potential to happen again. If it does the banana
producing industry will do what it did before we all ate
the cavendish variety, it will cultivate a new one.”
Monocots







Most monocots are non-woody or
herbaceous — their stems are soft and
fleshy.
Ornamental: orchids, lilies, tulips, and
other spring bulbs.
food for land animals: the most
important monocots are the grasses.
Cows and rabbits eat grasses, and
obtain energy from the leaves of grass.
Have bacteria in their digestive systems
that produce enzymes able to cut the
“crossties” in cellulose molecules, and
thereby release glucose units.
(mutualism.)
Humans do not have bacteria that can
digest grass blades (leaves), even if the
leaves are boiled or chopped.
We do, however, eat the seeds of
grasses.
Mmmm….





Humans can digest most of the matter in
the seeds of grass plants such as wheat,
corn, and rice – WE KNOW WHAT
HAPPENS WHEN YOU DON’T CHEW
YOU CORN!
Each of these seeds has large stores of
carbohydrates, along with smaller
amounts of protein and oils.
Wild grasses produce seeds much
smaller than those of today’s prairie
wheat.
Varieties have been developed that
produce more usable human food per
plant.
hybridization techniques have produced
new varieties of wheat, oats, and barley
that are both more climate-tolerant and
disease-resistant than earlier varieties.
Dicots (Mmm continued…)
 Most of Canada’s native tree
species are dicots.
 Some of these deciduous trees are
important economic resources in
Canada
 Most native wildflower species are
also dicots and a typical salad
contains a diversity of dicots such
as lettuce, tomatoes, radishes, and
sunflower sprouts.
 Only the onions are monocots.
 The staple foods of many cultures,
past and present, are dicots —
yams, potatoes, rutabaga, and
cabbage are all rich in starch.
 Bean seeds are rich in protein,
while bean pods are rich in
vitamins.