Without knowing the history of the name, it can't be definitively answered. Possibly: Rowanus (male). However, it might be more accurate as Rovanus. (There is no "W" in Latin; "V" is pronounced as we pronounce "W" in English.) Also, "Rowan" might be only part of an older name or term (shortened by time and use).
Rowan Joseph's birth name is Joseph Rowan.
Brent Rowan's birth name is Marlin Brent Rowan.
Dan Rowan's birth name is Daniel Hale Rowan.
Rowan Williams's birth name is Rowan Douglas Williams.
Rowan Atkinson's birth name is Rowan Sebastian Atkinson.
Rowan Merewood's birth name is Rowan Padhraic Merewood.
Rowan Pelling's birth name is Dorothy Rowan Pelling.
Jonathan Rowan's birth name is Jonathan Jermaine Minor Rowan.
The name Rowan means red
Rowan is Celtic/Gaelic.
The Bukshah's name in "Rowan of Rin" is Shaaran.
rowan the word ナナカマド nanakamado Rowan the name ローワン roowan