Biology 1108

1
Lecture 14

• Biology 1108
• Chapter 30 Plant Diversity II

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Learning Objectives

• Define
• Cultivated
• Sporophylls
• Recall
• Where how old earliest evidence of American
  agriculture
• Examples of each phylum
• Discuss
• Continued reduction of gametophyte
• Evolutionary significance of pollen

3
A Significant Seed

• A squash
• Found in cave, Oaxaca, Mexico
• 10,000 years old
• The earliest known cultivated plant in Americas
• Different from wild variants
• Shows agriculture started at same time as Asia
  Europe

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Circular Definition

• Rule of thumb never use a word to define a word
• P. 597 Seed plants are vascular plants that
  produce seeds.
• What changes would you make to this defintion?

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Important Reproductive Adaptations

• More reduction of the gametophyte
• Appearance and advancements of the seed
• Evolution of pollen

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Reduction of the Gametophyte

• In seed plants, theyre microscopic!
• Still are important for providing nourishment to
  young sporophyte (via seed)

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Seeds for Dispersal

• Seed embryonic sporophyte food all in a
  protective coat
• Embryo produced from egg sperm
• All seed plants heterosporous

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Megaspore Protection

• Integuments layers of sporophyte tissue
• Ovule integuments megasporangium megaspore
• Female gametophyte develops inside
• If egg is fertilized, whole ovule turns into a
  seed

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Pollen

• Microspores develop into pollen grains
• Upon reaching flower, pollen grain grows a pollen
  tube towards females ovule
• Sperms are produced delivered
• Pollen can travel hundreds of km
• Sperms from bryphytes cannot!

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7th Inning Stretch
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Gymnosperms

• Greek for naked seeds
• Do not have enclosed ovaries
• Utilize specialized leaves called sporophylls
• Include, among many others, the pines

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Ginkgophyta

• Ginkgo biloba the only species
• Unusual mobile sperm
• Good city tree
• Tolerates air pollution well

13
Cycadophyta

• Called the sago palms
• Look like palms (but arent)
• Palms have dates
• Cycads have cones
• Great websites
• The Cycad Pages
• Jurassic Park Plants
• Note sporophylls

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Gnetophyta

• Includes worlds weirdest plant
• Welwitschia websites
• NamibWeb.com
• Missouri Botanical Garden

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Coniferophyta

• The conifers (L. conus cone, ferre to carry)
• Mostly evergreen
• Include pines, redwoods, firs, spruces, yews,
  junipers, cypresses, cedars

16
Chemotherapy and Conservation

• Taxol was discovered in Pacific yew bark (Taxa
  brevifola)
• Loggers cannot use it
• After clear-cutting, they plant only trees they
  consider usefulnot Pacific yew
• Saving wild places may help to save people too!
• Bristol-Meyers Squibb website

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Exercise
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Answers
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Pine Lifecycle 1
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Pine Lifecycle 2
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Pine Lifecycle 3