The 1m-tall shrubs were planted by the New Zealand Transport Agency about a fortnight ago because it considered the memorial, of flowers, a distraction for motorists.
The memorial marks the spot where 19-year-old Devon Anderson, of Mosgiel, died in a car crash on June 22, 2003.
Ms Anderson's mother, Bronwyn, said she had been at the memorial on Saturday and the shrubs were still in place.
She was "quite sad" to learn the shrubs had since been torn out.
Although she had not been consulted over the planting and did not particularly like the choice of shrubs, she believed the agency had done a good job of planting them.
"I had no problem with them being there."
However, several people who had spoken to her were "brassed off" about the shrub screen.
The shrubs, on the northern side of the motorway, was planted after some motorists complained the memorial caused other motorists to lose concentration.
Rachael Brinsdon, in a letter to the Otago Daily Times, described the agency's decision to plant the shrubs as "absolutely crazy" and considered they were planted too close to "the garden".
"It should not be forgotten that a lovely young woman who was loved by many, died at the place where this garden is."
Agency regional network manager Murray Clarke said he would take another look at the issue but stressed that safety was the priority and "the rule" was that such places should be marked by no more than a white cross.
