Why do you cut a couple of inches off the stems of a bouquet ? Anything to do with vascular tissue?

I am curious about transpiration and what this has to do with it.

Why do you cut a couple of inches off the stems of a bouquet ? Anything to do with vascular tissue?
Transpiration (evaporation of water through plant stomata) remains in effect after the flower has been cut from the parent plant. Thus, water in the xylem is pulled up the remaining stem, and it is not replaced. By cutting off a portion of the remaining stem, you re-establish the transpirational stream, and thus the flower wilts at a reduced rate, in effect “apparently” living longer.





Some studies have shown that the break in the transpirational stream is nearly instantaneous. Thus, one needs to make the cuts under water to re-establish the stream.
Reply:When plants are cut, the leaves continue to transpire, using up the water that the xylem are transporting from where the roots used to be. If several inches are not cut off the bottom, the xylem will contain air pockets that, when they reach the flowers and leaves, cause shock. Cutting the bottom few inches off in a timely manner will eliminate the air bubble in the xylem, especially if the cutting is done underwater and the plant is immediately transported into a vase with water.





You can see the air bubbles if you take a stalk of celery with the leave still on and put it in water with food coloring for thirty minutes, take it out for fifteen, and put it back in for thirty (depending on the health of the celery stalk).
Reply:Unless they are freshly cut the ends have dried and water won't travel up the stems and keep the flowers looking pretty (they will wilt and dry up instead).





Cutting the ends off before placing them in a vase of water lengthens the amount of time the flowers will look pretty/fresh.