Yes
Flowers are parts of a plant. The plant has roots which have root hairs which suck up water. The roots also help anchor the plant in the ground so it does not get blown away.
Most cutting flowers are annuals. They have shallow root systems, usually about 4-6 inches. Some common cutting flowers with this root depth are zinnias, button flowers, straw flowers, and statice.
Flower is just a part of a plant or tree. The water is being absorbed through the root. Flowers absorb water through their roots.
There are no rose trees. There are roses bushes. They have branched root systems.
Bag roses usually = bare root roses. If you won't be planting them in a week or two, don't bother buying them. They won't make it.
roses reproduce by rhizomes, these resemble large roots but do not function the same as a true root
Depends on the type of flower and even at that different breeds of the same species can grow they're roots at different rates. Also taking into consideration additives that has been added to the plant soil or water that will allow for faster root growth. My best advice is to check on the specific flower your wanting to grow and find out that particular flowers/breeds root growth times.
The flowers and the leaves
Berberis
Ferns do not sprout flowers, instead they propagate via their root system; spreading underground.
potatoes are type of root vegetable so you're right!
Because they have been cut of from their root system that provides them with water.