Morphogenesis
generation of the shape of the plant and its various organs
Differentiation
an increase in complexity as some cells become different from each other
Polarity
having two different ends, usually a shoot/root polarity or a petiole/leaf tip polarity
Hormone
a chemical that is produced by one part of a plant, often in response to a stimulus, and then is transported to other parts and induces responses in appropriate sites
Satoliths
a type of starch grain that is so dense it sinks to the bottom of a cell’s cytoplasm, indicating the direction of gravity
Light
- photosynthesis
- direction or gradient of light which allows a plant to grow and orient its leaves toward sunlight which increases light availability for photosynthesis
- duration of light/length of day provides info about the time of year/season; needs to have enough time to be dormant
Gravity
- gravity causes weight stress so needs enough fibers to support its weight; bent from flooding or slipping from a hillside change growth to upright again
- roots know to grow down for nutrients and minerals and shoots grow up for photosynthesis, pollination and seed distribution
- force of gravity exerted on plant organs changes as the weight supported by the organ changes; if fruit like an apple develop must be able to support that with extra fibers
Touch
- plants grow around and against objects when they come into contact with them
- thick bark can be produced if branches rub against stone or another branch
- tendril growing around an object is beneficial for support; fly touch a venus fly trap it closes
- different plants respond in different ways to contact depending on the plant
Photoperiod
day length; the period of time that uninterrupted light is present
Critical night length
the length of darkness that must be exceeded by short-day periods, or not exceeded by long-day plants, for flowering to be initiated
Short day plants
a plant that is induced to flower by nights longer than the critical night length
Long day plants
a plant that is induced to flower by nights shorter than the critical night length
Endogeneous Rhythms
a rhythm generated entirely within an organism whose periodicity is not maintained by an external rhythm; certain aspects of their metabolism cycle is controlled by internal factors by an internal clock
Entrain
the resetting of an endogeneous rhythm by an exogeneous stimulus
Circadian rhythm
an endogeneous rhythm whose period is approximately 24 hours long
ABC model of flower organization
three fundamental genes ABC interact to control the basic aspects of flower organization; Gene A affects the outermost, lowest region of a flower shoot apical meristem, gene C controls the uppermost, central region and gene B partially overlaps the other two
