Selenicereus megalanthus, commonly known as the yellow dragon fruit or yellow pitahaya, is a climbing cactus species in the family Cactaceae. It is native to the high-altitude tropical regions of South America, specifically the Andean valleys of Colombia, Ecuador, Peru, and Bolivia. The genus name Selenicereus refers to Selene, the Greek moon goddess, highlighting the plant’s nocturnal flowering, while the species epithet megalanthus is derived from the Greek megas ("large") and anthos ("flower"), as it produces some of the largest blossoms in the cactus family. Historically, it has been harvested from the wild for centuries, but it has recently become a premier export crop, particularly from Colombia, prized as the premium variety of the dragon fruit family.

The plant is a hemi-epiphytic climber with slender, three-angled green stems that are less "leafy" and more heavily armed with small spines than its red-skinned relatives. Unlike the smooth-skinned S. undatus, the fruit of S. megalanthus is covered in small clusters of spines (isoles) that must be brushed off during harvest. The flowers are stunningly large, white, and bell-shaped, opening for only one night and emitting a potent fragrance to attract nocturnal pollinators like sphingid moths. It is considered more difficult to cultivate than other pitahayas, as it grows more slowly and is more sensitive to extreme temperatures.

The yellow dragon fruit is widely considered the most flavorful and sweetest of all dragon fruit varieties, often reaching a Brix (sugar content) level of 18 or higher. The flesh is translucent white, incredibly juicy, and filled with larger, crunchier black seeds than those found in red varieties. Its flavor is sophisticated, often compared to a blend of honey, lychee, and kiwi. In modern culinary applications, it is served chilled as a luxury fruit, used to sweeten high-end desserts, or utilized in "detox" juices. Due to its high sugar content and thin skin, it is more fragile for transport, which often accounts for its higher market price compared to red pitahayas. Yellow varieties of S. undatus are also called yellow dragon fruit but lack the spines and sweetness of S. megalanthus.

Nutritionally, Selenicereus megalanthus is a dense source of dietary fiber and Vitamin C. It is particularly famous for its concentrated levels of prebiotic oligosaccharides, which can have a pronounced laxative effect if consumed in large quantities—a trait that has earned it a reputation as a "natural digestive aid" in many cultures. The seeds are exceptionally high in polyunsaturated fatty acids, specifically linoleic acid (omega-6). The fruit also contains various phenolic compounds and flavonoids, though it lacks the betalains that give other dragon fruits their red pigment.