The term 'plant organ' can refer to a variety of structures that are found in plants. A LEAF is a flat, thin organ that is typically green and is used for photosynthesis. A pistil is the female reproductive organ of a flower, which contains the ovules. An OVULE is a small structure that contains the female gametes of a plant. Finally, a TENDRIL is a slender, thread-like organ that is used by some plants for support and climbing.