Fern fern ("Onoclea sensibilis"). Giant water fern ("Salvinia molesta") is one of the world's worst aquatic weeds. The important fossil fuel coal consists of the remains of primitive plants, including ferns. Ferns have been studied and found to be useful in the removal of heavy metals, especially arsenic, from the soil. Other ferns with some economic significance include: The study of ferns and other pteridophytes is called pteridology. A pteridologist is a specialist in the study of pteridophytes in a broader sense that includes the more distantly related lycophytes. Pteridomania is a term for the Victorian era craze of fern collecting
The Power of Movement in Plants to differing environments whilst at the same time answering some objections of his day that evolution could not account for changes in behavioural responses. In his conclusions, Darwin presents the key features of plants from an evolutionary perspective indicating that gradual modification of these processes in response to natural selective forces like light and water could enable extensive ability to adapt. The process that creates the circular or elliptical movement of the stem and tips of plants (circumnutation) was identified as a significant one in enabling plants to evolve and adapt to almost any environment on the planet. Darwin also