What is one of the longest plants in the world sometimes im green or sometimes im brown sometimes i have roots sometimes i have do not part of me is to manufacture ice cream?

One of the longest plants in the world is kelp, specifically giant kelp, which can grow up to 150 feet long. It can appear green due to its chlorophyll content, and brown when it dries out. Kelp has a holdfast that anchors it to the ocean floor but does not have true roots like land plants. Additionally, alginates derived from kelp are used in the food industry, including in the production of ice cream as a thickening agent.