I heard that dragonfruit requires 2 different varieties for properly setting fruit. So last year I bought a white fleshed and red fleshed unknown varieties.
I learned today that the red and white fleshed dragonfruits are different species from each other - the white is undatus and the red is costaricensis.
Does that mean I won’t be able to cross pollinate these with each other?
I don’t know the answer personally, but found a study that seems to say they set more and larger fruit when you use pollen from different species, and those two are likely cross-compatible (definitely at least one way):
In the Hylocereus spp., H. polyrhizus and H. costaricensis were self-unfruitful, and cross-pollination with other species led to high fruit set (100%). Hylocereus undatus was self-fruitful, setting fruit with self-pollen.
Pollen source influenced fruit weight. In the self-fruitful species of Hylocereus , fruit obtained by hand cross-pollination with other Hylocereus spp. were significantly heavier than fruit obtained by hand self-pollination.
Pollination of H. polyrhizus and H. costaricensis with fresh pollen of H. undatus (clone A) led to high fruit
set and heavy fruit.