Frank Jarman, who worked as a forester in Cape Town between 1893 and 1902, thought he was doing the country a favour by planting hundreds of pine and gum trees on the slopes of Table Mountain and Devil's Peak.
It appears that others did too, and there is a plaque to Jarman on Devil's Peak erected in 1904 which reads: "He found these barren, stony slopes treeless. He left them covered with forest."
A century later, when the damage alien plants do to indigenous vegetation is common knowledge, National Parks is spending hundreds of thousands of rand trying to get rid of the descendents of the pines and gums Jarman planted.
These have spread right up the mountain slopes, which, far from being barren, are covered with fynbos, one of the richest plant communities in the world.
On Thursday, a group of "high altitude" hackers, armed with ropes and chain saws, moved into some of the inaccessible slopes on the eastern face of Devil's Peak and began felling the aliens.
Augustine Morkel, a national parks ranger, said this was the first time in 20 years that there had been a concerted effort to clear up the inaccessible slopes. The team hopes to clear 40 hectares of pines and gums in a month at a cost of R118 000.
The contract to do the job has been given to Hein Carolus's company, Ceres Mountain Guides. The team is made up of men and women trained by the department of water affairs' Working for Water project.
One of the team is Xoliswa Tokwe, 47, of Wolsley, who has been an alien hacker for the past three years. Dressed in her overalls, helmet and visor, Tokwe whips her chainsaw around with an ease that comes of many hours practice.
"Before I did this, I was unemployed. Someone came to tell us about Working for Water in Wolsley and I joined them.
"Then they said they were going to train people to go up the mountains and there was an opportunity for ladies to go too, so I went. I was nervous in the beginning, but now I enjoy it," she said.
Chrystal Davids, 22, of Ceres, is delighted that they will be staying in National Parks accommodation with running water.
"Usually we camp out in the mountains in tents when we're hacking. Now we can wash after work and go out on the town," she grinned.