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 Different Forms of Flowers on Plants of the Same Species increase the fertility of this common plant. The same thing was found to occur in the primrose, as well as in flax (Linum perenne), lungworts (Pulmonaria), and a host of other plants, including the American partridge-berry (Mitchella repens). These are called dimorphic heterostyled plants. Still more extraordinary is the case of the common loosestrife (Lythrum salicaria), which has both stamens and styles of three distinct lengths, each flower having two sets of stamens and one style, all of different lengths, and arranged in three different ways: These flowers can be fertilised in eighteen distinct ways, necessitating a vast number of