It is not a hoax, but it is not natural either. It is quite a clever manipulation.
Here’s a related article:
"Strange Root
An artist using plants as his medium reminds us that nature is its own boss
By Sharon Mizota Wednesday, Jun 28 2006
Francis Baker’s artworks are topiaries in reverse. While shrub sculptors trim bushes to resemble swans and bunnies, Baker coaxes plant roots into eerie versions of familiar forms — a Barbie, a Buddha, an outstretched hand. His is an additive rather than subtractive process: He makes a mold of an everyday object, pots a plant in it, and lets nature do its thing. It can take years (the current series took five) for the sequoia, peace lily, or china doll plant’s roots to take on the shape of the mold, but when Baker finally frees the roots from their containers, the resulting mass of gnarled and twisted tendrils preternaturally maintains its intended outline. His photographs of these root sculptures are beautiful and creepy. A collaboration between the artist’s eye and nature’s primal impulse to grow, they’re simultaneously earthy and otherworldly."…
Entire article:
sfweekly.com/2006-06-28/culture/strange-root/ by