Axel Erlandson was a horticulturist known for shaping trees into unusual forms, a kind of bonsai on a large scale. He was born in Sweden in 1885 and moved to the United States with his parents as a child, and grew up to become a farmer in California.
According to a biography on Atlas Obscura, Erlandson began shaping trees after observing the natural bonding process known as inosculation. He used a combination of grafting and bending to guide the trunks into geometric forms. Soon, his wife and daughter suggested that he sell tickets to view the trees and Erlandson opened his attraction, The Tree Circus.
Many of the original trees died before Michael Bonfante, owner of Nob Hill Foods and a horticulture enthusiast undertook the project of rescuing the remaining trees. He opened Gilroy Gardens, and relocated the trees to their current home in 1985. According to their website, 25 of Erlandson's original trees remain on display, including his first, the "Four Legged Giant."
Here's a slightly wacky yet wonderful video of the trees' journey with 1980's footage:
Erlandson's work has inspired a number of artists and designers, with the promise of building living, organic structures. One such designer is Gorden Glaze, who hopes to grow living jungle gyms from trees.