Plant CharacteristicsPlant Characteristicsand Functionsand Functions

14.1 Classifying Plants14.1 Classifying Plants

Evolutionary HistoryEvolutionary History probable that

vascular and non-vascular plants have common ancestors with one group of the plant-like protists, the green algae

CeleryCelery

HornwortHornwort

What they have in What they have in common with protistscommon 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

DifferencesDifferences 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.

DifferencesDifferences

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 PlantsNon-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 PlantsNon-vascular Plants

Because diffusion is generally a slow Because diffusion is generally a slow process and they have no vascular process and they have no vascular tissue, non-vascular plants are tissue, non-vascular plants are restricted in size.

Uses of non-vascular Uses of non-vascular plantsplants

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.

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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 All trees living today are either one

or the otheror 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.

GymnospermsGymnosperms 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.

GymnospermsGymnosperms 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.

AngiospermsAngiosperms

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.

AngiospermsAngiosperms 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 Angiosperms: Monocots and Dicotsand 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.

MonocotsMonocots 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 foodMonocots 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 clonalOur bananas are clonal

http://www.askabiologist.org.uk/answers/viewtopic.php?id=123 http://www.askabiologist.org.uk/answers/viewtopic.php?id=123 ““Sometimes you can see very tiny dot-like seeds near Sometimes you can see very tiny dot-like seeds near

the centre of the banana, but they are infertile.  The the centre of the banana, but they are infertile.  The reason for this, is that edible (the non cooking variety) reason for this, is that edible (the non cooking variety) are clonal, and to the best of my knowledge, all the are clonal, and to the best of my knowledge, all the bananas eaten in the 'West' are the 'Cavedish variety'.  bananas eaten in the 'West' are the 'Cavedish variety'.  Being clonal the genetics of one banana plant and Being clonal the genetics of one banana plant and another is the same, and this means that they are another is the same, and this means that they are susceptible to diseases, and in the past cultivated susceptible to diseases, and in the past cultivated bananas have been destroyed by bilght.  This has the bananas have been destroyed by bilght.  This has the potential to happen again.  If it does the banana potential to happen again.  If it does the banana producing industry will do what it did before we all ate producing industry will do what it did before we all ate the cavendish variety, it will cultivate a new one.”the cavendish variety, it will cultivate a new one.”

MonocotsMonocots 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….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 Dicots (Mmm continued…)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.