William Brennan may refer to:
- William Brennan (Australian politician) (1865–1937), member of the New South Wales Parliament
- William Brennan (baseball) (born 1963), American baseball pitcher
- William C. Brennan (1918–2000), New York politician and judge
- William J. Brennan Jr. (1906–1997), justice of the United States Supreme Court
- William John Brennan (1938–2013), Australian Roman Catholic bishop
- William Joseph Brennan (bishop) (1904–1975), Roman Catholic priest in Australia
- Will Brennan (born 1998), American baseball player
- Willis Brennan (1893–1950), American football player
- Willy Brennan (died 1804), Irish highwayman
- Bill Brennan (umpire) (1880–1933), Major League Baseball umpire and college football coach
- Bill Brennan (boxer) (1893–1924), American boxer
- Bill Brennan (activist) (born 1968), candidate for Governor of New Jersey in 2017
- Bill Brennan (journalist), American sports journalist
- Billy Brennan (born 1934), British ice hockey player
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