No, lettuce is not cut when it flowers.
Specifically, the lettuce needs to be cut before it flowers unless you want it to taste bitter and unless you do not want the seeds. A lettuce that flowers should be allowed to seed. A lettuce that is cut before flowering may regenerate seconds if it is a particular variety, such as butterhead and looseleaf.
flowers... that have been cut...
Yes, cut lettuce does grow back after you cut it. When I was young, we had a garden and used our lettuce all the time. Just don't pick the whole plant.
cut.
cut flowers. fleurs coupées
It is believed that adding sugar to the water for cut flowers provides the flowers with a food source since the flowers have been literally "cut off" from their food supply.
The lettuce does not turn brown due to it being cut with a metal knife. It turns brown due to oxidation.
it kills bacteria in the water prolonging the life of cut flowers
Cut flowers will live for quite some time if you care for them properly.
Cut is an adjective in that sentence. It describes the noun flowers.
Adding 7-Up to the water in a vase of cut flowers is said to prolong the life of cut flowers. The lemon/lime juice in 7-Up lowers the pH level in the water, and cut flowers like a lower pH. Next, the sugar in 7-Up provides a food source for the cut flowers.
For cut flowers cut them when the first floret opens.
Live cut flowers have a limited life. The majority of cut flowers can be expected to last several days with proper care. Roses and Daisies have a really short life.