Germination, resumption of growth of a plant embryo contained in the seed after a period of reduced metabolic activity or dormancy. Conditions required for germination include an adequate water supply, sufficient oxygen, and a favorable temperature. Rapid uptake of water followed by increased rate of respiration are often the first signs of germination. During germination, stored food reserves are rapidly used up to provide the energy and raw materials required for the new growth. The embryonic root and shoot that break through the seed coat are termed the radicle and plumule, respectively. In hypogeal germination the seed leaves, or cotyledons, remain below the ground. In epigeal germination they grow above the ground and become the first photosynthetic organs.