Ferns are flowerless plants of the order 'Filicopsida' with beautiful green foliage. This ancient family of plants existed long back, around two hundred million years ago, much before the evolution of flowering plants. These garden plants with more than 12,000 species have long life spans and some of them are good indoor growers as well. 

 

Ferns vary in texture, height, shape and range in sizes from the tiniest button fern to the large Boston fern. Some of them forms a low spreading mound, while others create a bold upright clump. Many fern species shed its leaves annually, dying back to the ground for winter. Others are evergreen, providing attractive winter foliage in the garden, or are excellent for cut-flower arrangements.  

They are vascular plants i.e plants with well developed internal vessels or vein structures that promote the flow of water and nutrients. The large divided leaf of the fern is known as frond and they can be lacy or feathery, plain green or variegated. 

The fronds vary from simple undivided ribbons to intricately divided and subdivided masses of tiny leaflets and these leaflets that make up the whole frond are called pinnae (leaflet). These pinnae is attached along a long central stem called rachis. On the underneath of a fern frond, there are small clumps, spots or patches which are stuck onto the under surface of the pinnae. 

These are called spores and they grow inside casings called sporangia. The sporangia are tiny and may clump together into what are called sori.  (sorus-singular). They are the reproductive structures of the fern. Some ferns protect their sporangia with thin semi-transparent membranes called indusia. Sometimes the sporangia are tucked under a curled-over part of the margin of the pinnae.