LE 30-4bb Pacific yew. The bark of Pacific yew (Taxa brevifolia) is a source of taxol, a compound used to treat women with ovarian cancer. The leaves of a European yew species produce a similar compound, which can be harvested without destroying the plants. Pharmaceutical companies are now refining techniques for synthesizing drugs with taxol-like properties.

LE 30-4bc Bristlecone pine. This species (Pinus longaeva), which is found in the White Mountains of California, includes some of the oldest living organisms, reaching ages of more than 4,600 years. One tree (not shown here) is called Methuselah because it may be the world’s oldest living tree. In order to protect the tree, scientists keep its location a secret.

LE 30-4bd Sequoia. This giant sequoia (Sequoiadendron giganteum), in California’s Sequoia National Park weighs about 2,500 metric tons, equivalent to about 24 blue whales (the largest animals), or 40,000 people. Giant sequoias are the largest living organisms and also some of the most ancient, with some estimated to be between 1,800 and 2,700 years old. Their cousins, the coast redwoods (Sequoia sempervirens), grow to heights of more than 110 meters (taller than the Statue of Liberty) and are found only in a narrow coastal strip of northern California.

LE 30-4be Common juniper. The “berries” of the common juniper (Juniperus communis), are actually ovule- producing cones consisting of fleshy sporophylls.

LE 30-4bf Wollemia pine. Survivors of a confer group once known only from fossils, living Wollemia pines (Wollemia nobilis), were discovered in 1994 in a national park only 150 kilometers from Sydney, Australia. The species consists of just 40 known individuals two small groves. The inset photo compares the leaves of this “living fossil” with actual fossils.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Gymnosperm Evolution Fossil evidence reveals that by the late Devonian period some plants, called progymnosperms, had begun to acquire some adaptations that characterize seed plants

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Gymnosperms appear early in the fossil record and dominated the Mesozoic terrestrial ecosystems Living seed plants can be divided into two clades: gymnosperms and angiosperms

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A Closer Look at the Life Cycle of a Pine Key features of the gymnosperm life cycle: – Dominance of the sporophyte generation – Development of seeds from fertilized ovules – The transfer of sperm to ovules by pollen The life cycle of a pine is an example Animation: Pine Life Cycle Animation: Pine Life Cycle

LE 30-6_3 Mature sporophyte (2n) Pollen cone Microsporocytes (2n) Longitudinal section of pollen cone Ovulate cone Longitudinal section of ovulate cone Micropyle Ovule Key Haploid (n) Diploid (2n) Megasporocyte (2n) Integument Megasporangium Germinating pollen grain Pollen grains (n) (containing male gametophytes) MEIOSIS Microsporangium Sporophyll MEIOSIS Germinating pollen grain Female gametophyte Archegonium Egg (n) Germinating pollen grain (n) Integument Discharged sperm nucleus (n) Pollen tube Egg nucleus (n) FERTILIZATION Embryo (new sporophyte) (2n) Food reserves (gametophyte tissue) (n) Seed coat (derived from parent sporophyte) (2n) Seedling Seeds on surface of ovulate scale Surviving megaspore (n)

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 30.3: The reproductive adaptations of angiosperms include flowers and fruits Angiosperms are flowering plants These seed plants have reproductive structures called flowers and fruits They are the most widespread and diverse of all plants

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Characteristics of Angiosperms All angiosperms are classified in a single phylum, Anthophyta The name comes from the Greek anthos, flower

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Flowers The flower is an angiosperm structure specialized for sexual reproduction A flower is a specialized shoot with up to four types of modified leaves: – Sepals, which enclose the flower – Petals, which are brightly colored and attract pollinators – Stamens, which produce pollen – Carpels, which produce ovules

LE 30-7 Stamen Filament Anther Stigma Carpel Style Ovary Petal Receptacle Ovule Sepal

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Video: Flower Blooming (time lapse) Video: Flower Blooming (time lapse)

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Fruits A fruit typically consists of a mature ovary but can also include other flower parts Fruits protect seeds and aid in their dispersal Mature fruits can be either fleshy or dry Animation: Fruit Development Animation: Fruit Development

LE 30-8 Tomato, a fleshy fruit with soft outer and inner layers of pericarp Ruby grapefruit, a fleshy fruit with a hard outer layer and soft inner layer of pericarp Milkweed, a dry fruit that splits open at maturity Walnut, a dry fruit that remains closed at maturity Nectarine, a fleshy fruit with a soft outer layer and hard inner layer (pit) of pericarp

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Various fruit adaptations help disperse seeds Seeds can be carried by wind, water, or animals to new locations

LE 30-9 Wings enable maple fruits to be easily carried by the wind. Seeds within berries and other edible fruits are often dispersed in animal feces. The barbs of cockleburs facilitate seed dispersal by allowing these fruits to hitchhike on animals.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Angiosperm Life Cycle In the angiosperm life cycle, double fertilization occurs when a pollen tube discharges two sperm into the female gametophyte within an ovule One sperm fertilizes the egg, while the other combines with two nuclei in the central cell of the female gametophyte and initiates development of food-storing endosperm The endosperm nourishes the developing embryo