selenicereus

Anthonys Rick-Rack. This curious epiphyte is grown for the strange leaves which lend it the common name Ric-Rac Cactus, Zig-Zag or Fishbone Cactus. In the wild it attaches itself to trees, clinging by little aerial root filaments along the zigzagging succulent leaves, but is adaptable to terrestrial habits. It loves strong yet indirect lighting. It does not need a lot of water and should be permitted to dry out entirely between waterings. It is nightblooming and its flowers last only a single night in spring.

Very rare Yellow Pitaya. This cactus originates from Bolivia, Equador, Peru and Columbia. It's greatly known for it's sweet tasting fruit. Knobbed, yellow cactus fruit sharing some similarities with the Hylocereus dragon fruit (pitaya). Taste is said to be superior to most cactus fruits. The fruits are smaller than the common dragon fruit, and contain prominent spikes until ripening time, upon which the spikes drop off.
Lean more:
Pitaya page
What to do with a Dragon fruit?