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 Secret Life of Plants plants "might originate in a supramaterial world of cosmic beings which, as fairies, elves, gnomes, sylphs, and a host of other creatures, were a matter of direct vision and experience to clairvoyants among the Celts and other sensitives." The book has been criticized by botanists such as Arthur Galston for endorsing pseudoscientific claims. According to Galston and physiologist Clifford L. Slayman many of the claims in the book are false or unsupported by independent verification and replicable studies. Botanist Leslie Audus noted that the book is filled with nonsensical "outrageous" claims and should be regarded as fiction. The book was