Parling toured with England to Australia in 2010 but he returned home with a neck problem and then suffered a succession of knee injuries which kept him out of England contention until this season.
In both his appearances in the Championship, Parling has replaced Palmer and is now set to take his place alongside Saracens' Mouritz Botha, with Rowntree acknowledging there have been lineout issues.
"We were nine from 11 in Scotland and 14 from 17 in Italy, with sleet all over the ball against a very competent Italian pack," said Rowntree.
"Not all of it was clean so I am looking to improve our delivery and certainly the tempo at which we go about our line-out."
Meanwhile, Rowntree admits England are desperate to match Wales' attacking firepower at Twickenham on Saturday, labelling their visit the acid test for Stuart Lancaster's new-look team.
Both England and Wales have won their opening two RBS 6 Nations matches but while Warren Gatland's side have run in six tries, Saturday's hosts have managed just two - both charge-down efforts from fly-half Charlie Hodgson.
Wales will cross the Severn Bridge as the stand-out favourites in a match that could go a long way to deciding who wins the Championship with Rowntree admitting England have not come up against a team of their calibre yet.
"Wales play at an intensity, a speed and physicality we haven't played against yet," said Rowntree.
"We've spoken about being ten per cent better at every component of our game.
"They pose challenges all over the field from the set-piece to the break-down and with the amount of people in space you have to mark them all the time.
"We've had two difficult away games but I look at our training and our resolve in the game as being massive improvements and I'm happy with where we're going.
"The next stage is to transfer that on to the field and we are desperate to score more tries."
And while being the underdogs at Twickenham might not be something England sides are used to, Rowntree is relishing the test that awaits this weekend.
"They are the form team of the championship so far, and they will be coming to Twickenham and fancying their chances," he added.
"They are a team who are always in it until the last minute of the game, always threatening to break free.
"The prospect of Wales coming to our fortress as favourites is a great challenge for this group.
"At our stage of development as a team, it's just the challenge we need."