Greentree has been assigned to Rockford.
Greentree, 25, appeared in two games with the Flames last season, spending the majority of the campaign with the AHL’s Quad City Flames where he led the club with career highs in goals (39) and points (76) while appearing in 79 of 80 regular-season contests. Greentree, who was on the roster of Calgary’s AHL affiliate Abbotsford Heat at the time of the trade, has been held scoreless in four career National Hockey League matchups, which includes two with the Philadelphia Flyers in 2007-08.
The Victoria, B.C., native has recorded 126 points (65 goals, 61 assists) and 148 penalty minutes in 159 career AHL regular-season games in parts of three professional seasons with the Philadelphia Phantoms (2006-08) and Quad City (2008-09).
Prior to turning pro, Greentree skated for three seasons at the University of Alaska-Fairbanks (CCHA), racking up 41 goals, 60 assists, 101 points and 167 penalty minutes in 115 career games.
Johnson, who has not appeared in any games with the Blackhawks this season, tallied eight points (3g, 5a) in 38 matchups with the club last season, his first as a member of the organization after signing as a free agent on July 15, 2008.