If chloroplasts are what make a leaf appear green and they are only present in leaves, why does the stem of an herbaceous plant also appear green?
Actually, chloroplasts are found in both the leaf and stem cells of herbaceous plants, making these structures appear green. Chloroplasts contain the green pigment chlorophyll, a molecule responsible for absorbing the light energy used in photosynthesis. Chlorophyll pigments are also responsible for the green color of chloroplasts.