Flowering Plants Virtual Science University 1 Flowering Plants - - PowerPoint PPT Presentation

Flowering Plants

Virtual Science University

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Flowering Plants

Texas TEK B.10 (C) Student will analyze and identify characteristics of plant systems and subsystems.

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Flower, Your Scent Is So Sweet

Flower, Your Scent Is So Sweet! Flower, where is your little Stigma? Flower, where is your little Stamen? Flower, Let’s mix in a little pollen Oh! Oh! It smells like Cinnamon, Oh So Sweet! Flower, is your Carpel made up Of a Stigma and Ovary? Flower, is your Stamen made up Of an anther releasing Pollen Flower! Your Scent is So Sweet! -3X

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Introduction to Flowering Plants

• If you have ever stopped

to smell the roses, then you are familiar with the largest group of plants, the Angiospermae.

• The distinctive feature of

this group is the flower, a cluster of highly- specialized leaves which participate in reproduction.

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Introduction to Flowering Plants

• Not all flowers are as

conspicuous as the plant blossom in the picture

• Oaks, ivy, & grasses

also produce flowers, but because they are not as showy we often do not notice them.

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Introduction to Flowering Plants

• The flowering

plants are important in many ways above and beyond their appeal in flower arrangements.

• Not a day goes by

in which our lives are not affected by flowering plants.

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Introduction to Flowering Plants

• Nearly all of our food

comes from flowering plants; grains, beans, nuts, fruits, vegetables, herbs and spices almost all come from plants with flowers, as do tea, coffee, chocolate, wine, beer, tequila, & cola.

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Introduction to Flowering Plants

• Much of our clothing

comes from them as well -- cotton and linen are made from "fibers"

• f flowering plants, as

are rope and burlap, and many commercial dyes are extracted from other flowering plants.

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Introduction to Flowering Plants

• We also owe them

credit for a large number of our drugs, including over-the- counter medicines such as aspirin, prescribed drugs such as digitalis and atropine, and controlled drugs such as opium, cocaine, and tobacco.

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Fossilized Record It is a mystery?

• The rapid diversification of angiosperm taxa began in the

Albian, in the mid-Cretaceous, 144 to 65 million years ago, and has continued to this day.

• At that time, there is an almost exponential increase in

angiosperm diversity, and there does not appear to have been any major extinctions of groups in between.

• Despite the large numbers of taxa that are known from

rather early in this diversification, there is no indication of where the taxa are coming from.

• D.I. Axelrod has suggested that we do not find early

angiosperm fossils because the earliest angiosperms lived in dry, upland habitats where they were unlikely to be preserved as fossils.

• Though this idea has long been accepted, it has not

been well investigated and so remains to be tested.

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Structure of a Flowering Plant

• Like other seed plants,

angiosperms are heterosporangiate

– producing pollen and

• vules in different organs
• Unlike most seed plants,

however, the pollen and

• vule-bearing organs are

usually produced together in a bisporangiate cluster called a flower.

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Structure of a Flowering Plant

• In the center of a

typical flower are the carpels, modified leaves which enclose the ovules.

• These are often

fused to form a single pistil in the center of the flower.

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Structure of a Flowering Plant

• Surrounding the carpels

are several narrow stalks topped by pollen sacs; these pollen- bearing stalks are called stamens.

• Around these

reproductive organs is the perianth, usually consisting of an outer whorl of sepals and an inner whorl of petals.

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Structure of a Flowering Plant

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Structure of a Flowering Plant

• In monocots and

"primitive" dicots, the sepals and petals may be indistinguishable, as in the lily shown at right.

• In this case the

perianth parts are called petals.

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Structure of a Flowering Plant

• The first flowering plants

had numerous floral parts spiralled around a central axis, much like the flowers

• f Magnolia.
• In most angiosperms,

however, the floral parts are relatively few, and are arranged in a whorl, in which a set of parts are all attached around the central axis at the same level, instead of being attached in a staggered spiral.

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Structure of a Flowering Plant

• The parts of these earliest

flowers were likely very large and radialy arranged; they were not fused to each other, as is common in many groups today.

• In many angiosperms, the

flowers are arranged in clusters called inflorescences.

• The flowers may be attached

along a tall stalk, arranged in broad open clusters, or pressed tightly together so that the cluster looks like a single flower.

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What Does Angiosperm Mean?

• Angiosperms differ from
• ther seed plants in that

they enclose their ovules (and seeds) within a carpel.

• The carpel is a modified

leaf bearing the ovules, but the carpel is folded

• nto itself, wrapping the
• vules inside.
• The "vessel" which the

carpel forms gives the angiosperms their name.

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What Does Angiosperm Mean?

• Although the carpels are hypothesized to give

extra protection to the developing ovules and seeds, there is a problem with encasing the

• vules -- how to get the pollen to the ovule so

that it can deliver the sperm?

• In angiopserms, the pollen tube does not

simply grow through an opening in the tissue surrounding the ovule, but it must penetrate and grow through the tissue.

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Fertilization

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Angiosperm Reproduction

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Contact Information

www.VirtualScienceUniversity.com

1-877-920-5550

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