Biology 2500

1
Lecture 17

• Biology 2500
• Chapter 20 Gymnosperms

2
Learning Objectives

• Contrast
• Perfect vs. imperfect flowers
• Stamenate vs. carpellate
• Superior vs. Inferior
• Hypo/Epi/Perigynous
• Define
• Self incompatibility

3
Early Announcement Next Exam

• Monday, March 31st
• Test coverage through next Wednesday

4
Perfect vs. Imperfect

• Perfect flowers
• Have both stamens and carpals
• Bisexual
• Imperfect flowers
• Staminate flowers
• Carpellate flowers

5
Monoecious vs. Dioecious

• Monos single, oikos house
• Both sexes live on the same plant
• Flowers can be perfect or imperfect
• Dioecious
• Sexes live on separate plants
• Can ONLY have imperfect flowers

6
Superior vs. Inferior

• Refers to ovaries!
• Superior ovary
• Sepals, petals, stamens attached below the ovary
• Inferior ovary
• Sepals, petals, stamens attached near top of ovary

7
Hypo/Epi/Perigynous

• Refers only to perianth and stamens
• Remember perianth all sepals all petals
• Hypogynous attached below ovary
• Free from calyx
• Epigynous attached to top of ovary
• Perigynous stamens and petals fuse with calyx

8
Regular vs. Irregular

• Regular flowers
• Have radial symmetry (like starfish)
• Examples
• Photokey to Wildflowers website
• Irregular flowers
• Have bilateral symmetry (like humans)
• Examples
• Snapdragons
• Orchids (Lindas Orchid website orchidlady.com)

9
7th Inning Stretch
10
Hay Fever

• Due to wind-borne pollen
• Lands on moist nasal linings
• Releases proteins involved in fertilization
• Some people highly allergic to these

11
Double Fertilization

• Thought to have originated from second embryo
  being fertilized
• Modified over time so that other things occurred
• Nutritious endosperm is formed
• Ovule forms the seed
• Zygote develops into an embryo
• Ovary develops into a fruit

12
Outcrossing Avoids Inbreeding

• Dioecious plants
• Two sexes of plants
• Self-pollination impossible
• Monoecious plants
• Utilize dichogamystamens and carpels mature at
  different times
• Protandrous stamens first
• Protogynous carpels first

13
Genetic Self-incompatibility

• Occurs in some plants
• Self fertilization prevented by control of pollen
  tube growth
• If pollen lands on own stigma, pollen tube not
  allowed to grow properly
• The opposite of blood type
• With organ donors, a mismatch results in
  rejection
• With self incompatibility, a match results in
  rejection

14
Self Pollination

• Produces genetically similar plant population
• Advantageous if genetics well-suited to the
  environment
• Does not require pollinator
• Useful in areas w/o many birds or insects
• Mountain regions
• Arctic