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19 Cards in this Set

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Thigmotropism
Right: tendrils of the bur cucumber Cucumis anguria
Diurnal movement of wood sorrel leaves, Oxalis
Chrysanthemum, a short-day plant Left: short-day conditions; right: long-day conditions
Morphogenic response of Poinsettia (flower formation) to short days
Spinach, a long-day plant Left: short-day conditions; right: long-day conditions
Etiolated seedling needs exposure to red light to turn green
Etiolation: plant that is dark-grown, or under soil is thin and pale. They become green and sturdier when exposed to red light. Exposure to far-red light will cancel the effect
Thigmonastic movement (after touching) in Mimosa pudica
Venus flytrap thigmonastic movment
Thigmomorphogenesis
Regular rubbing inhibits elongation, but promotes radial expansion of plants
Left Arabidopsis plant was rubbed.
Heliotropism (of lupine) Leaves move and stay perpendicular to sun’s rays
Heliotropism (solar tracking) of sunflowers
Tropism
Bending of plant towards or away from stimulus
Positive: towards stimulus
Negative: away from stimulus
1. Phototropism
2. Gravitropism:
3. Hydrotropism:
4.Thigmotropism:
1.movement because of light
2.in response to gravity
3. in response to moisture
4. in response to touch
The Floral Stimulus
Florigen is the flowering substance.
It is formed in mature leaves and transported through the phloem to the apical meristem where it triggers a series of gene activities leading to flowers.
Florigen production seems to be dependent on day length.
Vernalization
Vernalization is exposure of plants to cold.
Needed for some plants to flower.
Takes place in shoot of apical meristem
Required for many biennials, winter annuals (sown in fall, bloom next spring)
Dormancy
Special condition of arrested growth.
Growth resumes when limiting conditions disappear
What are the triggers for growth for buds, seeds?
There are endogenous inhibitors that must be removed.
Seeds and dormancy
Environmental cues to break dormancy:
Warm temperatures after a long period of cold
Exposure to moisture after a period of drying
Abrasion by soil activities wearing away a protective coat: scarification
Microbial digestion of seed coat
Leaching away of inhibitory chemicals

Some seeds remain viable for a long time: a 2000 year old date palm; a 1300 year old lotus
1. Nastic movements
2. Nyctinastic movement
3. Thigmonastic movements
4. Photonastic
5. Morphogenic responses
6. Taxis
7. Thigmomorphogenesis
8. Heliotropism
1. non-growth response, no orientation with regard to direction of stimulus
2. sleep movement of leaves, vertical at night
3. (turgor changes)
4. opening and closing of flower parts: diurnal or nocturnal
5. fundamental changes in plants life stages (vegetative > reproductive)
6, cell swimming away from or towards stimulus (sperm cells of algae and some plants)
7. altering growth patterns: touching increases radial growth
8. solar tracking
Pulvinus
thickening at the base of plant parts that show nastic movements. Turgor change in parenchyma cells cause movement
Example: Mimosa pudica