Opening and Closing Mechanism
of Oxalis pes-caprae
Purpose: The plant Oxalis pes-caprae, or better known as Sour Grass (and also Bermuda Buttercup), is a small weedy plant that is distinguished by its bright yellow flowers. It is observed that the flowers of the plant open in the morning sun and consequently close in the late afternoon. The purpose of this experiment is to determine what physically causes the flowers to open and close.

Hypothesis: Considering the main components of the plant, water and plant stuff, the hypothesis is that the plant operates by removing or forcing water into the flower to cause it to open and close. Therefore, if several different processes are applied which would affect the amount of water, then eventually one of these processes would cause the opening and closing of the plant.

Equipment: Required for this experiment are many specimens of the sour grass plant (identified by yellow flowers atop a leafless stem. At the base of the plant there are many leaves that are tri-foliate (3 leaves) and clover shaped). A Microwave, Ice, Seltzer water, Hydrogen peroxide, glasses to hold specimens, salt, and pen and paper.

Step #1: Effects of temperature
Cut off two flowers and place one in boiling water and see effects, place the other in freezing water and observe effects. Finally, place the plant in normal water and place in the microwave, and place another plant in normal water and place in the freezer and observe effects.
Step #2: Effects of light
Place an object over one of the plants that will shade it from any sunlight, remove the object 15 minutes later and view effects. Remove one the specimens and place in complete darkness and observe, and finally remove all the petals off one of the plants and observe effects.
Step#3: Effects of pressure
Cut off one of the flowers, and suck at the base of the stem, notice any effects, secondly blow into the base of the stem. Place one of the specimens into salt water, another into Hydrogen peroxide, and finally another into seltzer water and observe any effects.

Type of Effect place upon Plant
Placement of plant into boiling water. The Plant instantly weathered into near nothingness. However, the flowers of the plant remained open.
Placement of plant into Freezing water The Plant seemed unaffected by the freezing water.
Placement of plant into microwave and set on high for 3 seconds. The Plant's stem dissolved in roughly 3 seconds, however the flowers of the plant stayed open.
Placement of plant into the freezer for extended period of time. The plant froze, and the stem was easily broken when pressure was applied, however the flowers remained open.
Plant Left intact, however, object shading it from Light. No effect on flowers
Plant removed and placed in shaded room. No effect on flowers
Petals of plant removed to stop photosynthesis of plant. No effect on flowers
Plant Placed in a salt water solution. No effect on flowers
Plant placed in a hydrogen peroxide solution. No effect on flowers
Plant Placed in a carbonated water solution. No effects on flowers
Air Sucked out of stem and flower. No effects on flowers.
Air pushed into stem and flower. No effects on flowers

Conclusions: It was apparent that nothing was able to cause the flower petals to close. The larger surprise was the fact that removal of light and photosynthesis processes did not cause the plant to close at it was believed that it is a function of how much photosynthesis is occurring that would cause the flowers to open. New experimentation will have to occur on the pes-caprae centering on time as the general cause of the opening and closing of the flowers. 

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