The gunwale (/ˈɡʌnəl/) is the top edge of the hull of a ship or boat.[1]
Originally the structure was the "gun wale" on a sailing warship, a horizontal reinforcing band added at and above the level of a gun deck to offset the stresses created by firing artillery. Over time it remained as a valuable stiffener mounted inboard of the sheer strake on commercial and recreational craft. In modern boats, it is the top edge of the hull where there is usually some form of stiffening, often in the form of traditional wooden boat construction members called the "inwale" and "outwale".
On a canoe, the gunwale is typically the widened edge at the top of its hull, reinforced with wood, plastic or aluminum, to carry the thwarts.
On a narrowboat or canal boat, the gunwale is synonymous with the side deck[citation needed]—a narrow ledge running the full length of the craft.
Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
View the detailed Guide of Psilotum nudum: Detailed Study Of Psilotum Nudum (Whisk Fern), Classification, Anatomy, Reproduction