modified plant parts

1
modified plant parts

• storage stem (tuber) potato
• evidence eyes are buds, chlorophyll
• floating leaves Salvinia, Victoria
• prop roots corn (from side of stem)

2
modified shoot

• onion
• fleshy leaf bases
• apical meristem at base

3
adaptive strategies

• parasites plants that steal nutrients
• mistletoe takes water
• indian pipe takes food and water.
• epiphytes plants sit on other plants
• evergreen leaves survive dry season
• deciduous leaves fall in dry season

4
fall leaf color

• chlorophyll degrades
• yellow/orange carotenoids visible
• red/purple anthocyanin is sunscreen

5
pigment locations

• anthocyanin vacuole purple, red, blue
• 95 of cell volume
• chlorophyll (PS) chloroplasts green
• carotenoids chromoplasts chloroplasts
  yellow/orange/red
• other plastids store starch

6
adaptation to desert

• stems or leaves for water storage
• green stems, spine leaves or branches
• stomata open at night
• convergent evolution

7
adaptation to low N habitat

• modified leaves for capturing animals
• 1) venus fly trap hairs close cage
• 2) pitcher plant slippery, hairs
• 3) sundew sticky hairs

8
adaptations to temperate deciduous forest

• 1) spring ephemerals
• small, herbaceous (not woody)
• early start in forest
• bloom before shade
• 2) trees
• flower before leaves
• showy flowers after leaves

9
types of roots

• tap fibrous

one main root, few side roots carrots, olive
trees erosion on hillsides
many roots hold soil grasses,
incl. bamboo prevent erosion
10
adaptation to prairie

• deep roots (often fibrous)
• grasses w/rhizomes, basal meristems
• survive fire (req. to kill woody competitors)

11
adaptation to forest fire
well formed trees little undergrowth

• no fire w/firegt

poorly formed trees much undergrowth
12
adaptation to forest fire
little undergrowth quick fire trees survive
thick bark
13
symbioses with plant roots

• 1) N-fixing bacteria
• eg Rhizobium assoc. with legumes
• plant makes nodules
• bacterium gets sugar
• plant gets N
• crop rotations
• pesticides may interfere
• Mt. St. Helens recovery

14
symbioses with plant roots

• 2) mycorrhizae fungus roots
• some roots modified, highly branched
• fungus gets sugar
• plant gets surface area, antibiotics
• gt95 of vasc. plants
• agriculture, plant with fungal spores

15
evolution of root symbioses

• mycorrhizae ancient (400 mya)
• root nodules recent (65-150 mya)
• plant genes assoc. w/ root nodules same as ones
  for mycorrhizae
• similarity of chemical signals
• hypothesis evolutionary relationship

16
root parasites

• nematodes
• live inside root
• carrots, potatoes, corn
• take nutrients from plant
• damage plant, open to infection

17
Other parasites
Beech infected with another species of
Phytophthora