Mare Erythraeum /ɛrɪˈθriːəm/ is a very large dark dusky region of Mars that can be viewed by even a small telescope. Its name comes from the Latin for the Erythraean Sea because it was originally thought to be a large sea of liquid water. It was included in Percival Lowell's 1895 map of Mars.[1]
Under the name of De La Rue Ocean it was included in Procter's 1905 map of Mars.
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