Pinnules are small, feather-like structures that grow from a larger frond or leaf. They are often found on ferns, and serve to increase the surface area of the leaf for improved photosynthesis. Synonyms for pinnules include leaflets, lobes, blades, segments, and divisions. Each of these terms describes a part of a larger leaf structure that is separate in some way from the main body of the leaf. Leaflets and pinnules are often used interchangeably, but blade refers specifically to the large, flat part of a leaf. Segments and lobes describe smaller, distinct parts of a leaf that are often separated by indentations or small stems.