Biology 2500: Botany

1
Lecture 21

• Biology 2500 Botany
• Chapter 22 Evolution of the Angiosperms

2
Learning Objectives

• Match
• A flower to its pollinator
• Contrast
• Dehiscent and Indehiscent seed dispersal

3
Question for Thought

• Why do bird-pollinated flowers have little scent?
• Give two good explanations

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Bird-pollinated Flowers

• Usually copious amounts of nectar
• Birds require lots of energy
• Nectar usually unavailable to insects
• Insects would never move to other flowers, due to
  low energy requirements
• Long corolla tubes

5
Scent Color of Bird Flowers

• Little scentwhy?
• Most birds cannot smell well
• Scent attracts insects
• Generally very colorful, esp. red
• Birds notice, insects dont

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Bats Flowers

• Flowers usually dull color
• Smell powerfulwhy?
• Like bird flowers, often tubular
• Floral accommodations for bats
• Some are on tree trunks
• Others hang on stalks below branches
• Bats also disperse seeds in droppings
• Bats pollinate bananas!

7
Wind-Pollinated Flowers

• No nectar
• Dull colors
• Odorless
• Ex
• The grasses

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7th Inning Stretch
9
Simple Fruit

• One fruit from one ovary
• Includes
• Berries
• Drupes
• Pomes
• See U of Arizona website

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Berries

• All fleshy
• Often many seeds
• Ex
• Tomatoes

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Drupes

• One to several carpels
• Each contains single seed, surrounded by a stone
• Ex
• Cherries
• Olives
• Peaches
• Plums
• And (with green skin still on)
• Coconut
• Walnut
• Almond

12
Pomes

• Occur only with some members of Rosaceae (rose
  family)
• Compound, inferior ovary
• MUST have a core
• Ex apples, pears

13
Aggregate Fruit

• A fruit from
• One flower
• An Aggregate fruit comes from A flower
• Several ovaries
• Ex blackberry, strawberry
• See UIUC Strawberry website

14
Multiple Fruits

• Fruits of several flowers squeezed together to
  form just one
• Multiple fruits come from multiple flowers
• Ex
• Fig
• Pineapple (the core is actually the stem)
• Sweetgum (see U of Florida website)

15
Seed Dispersal

• Dehiscent Mature ovary wall breaks open to free
  seeds
• Ex all bean pods
• Indehiscent Seeds remain IN the fruit