The growth form of giant kelp (Macrocystis pyrifera) is composed of shoots known as stipes instead of branches. From one parent holding fast to the hard bottom might come as many as 150 stipes. Typically, the tips of the biggest kelp bob at the ocean surface and calm the waters, appearing as patches of gold visible from land—a sign of the good health of the ecosystem that it anchors. But the kelp, as San Diego knows it, is in trouble.