His marriage record to Elizabeth Jutting is on Ancestry and lists his parents as Berend Hauen Blau and Imke Jans (Maas) Blau.
Information is from the Find A Grave website
I have found references to him as Howard Blaw on the marriage records for some of the children. He is also indexed as Hans by the transcribers. It is Haue on his tombstone.
↑ Find A Grave, database and images (https://www.findagrave.com : accessed 23 June 2018), memorial page for Haue Blau (Feb 1840–5 Nov 1904), Find A Grave Memorial no. 147128337, citing First Presbyterian Church Cemetery, George, Lyon County, Iowa, USA ; Maintained by DM Scott (contributor 47110289) .