Gleason family

Good day! My great great great grandfather was John Gleason born 1804 +/- . He emigrated to the United States ,according to the documents I have found, in 1840. The paperwork states that he came from Glenkeen , Tipperary . The documents also said he was a 'widower'  with 6 children, although the 1850 Federal U.S. Census only lists 5...Edward (b. 1830) , Martha (b.1832), Sarah (b.1833), Alice (b.1835) & John (b.1839). No mention of a Mom in the census... Any help , any info will be deeply appreciated as I try to find my Irish family and their story. Thanks, Marsha Whittemore