Hylocereus is a genus often referred to as "night-blooming cactus" (though the term is also used for many other cacti). Several species have large edible fruits, which are known as pitahayas or dragonfruits.
Hylocereus calcaratus - Costa Rica. Stems soft, green with distinctly lobed stems. Flowers 35–37 cm long, 20–30 cm wide.
Hylocereus costaricensis - (incl. Hylocereus polyrhizus of gardens) Costa Rica and Nicaragua to Peru. Stems waxy-white without horny margins. Flowers ca. 30 cm long with large bracts, usually with purple margins. Fruit red with purple pulpa.
Hylocereus escuintlensis - Guatemala. Stems green not glaucous, brown-margined. Flowers 28–31 cm long, 24–36 cm wide.
Hylocereus megalanthus - Stems green, slender without horny margins. Flowers 30–38 cm long with large flattened tubercles and small bracts. Flowers similar to Selenicereus. Fruit yellow.
Hylocereus minutiflorus - Guatemala, Honduras. Stems green. Flowers with rigid spines at base of flower, 5 cm long, 8–9 cm wide, white.
Hylocereus monacanthus - (incl. Hylocereus lemairei) Costa Rica to N South America. Stems gray-green without horny margins. Flowers ca 30 cm long, petals white, tinged pinkish near base or entirely pink. Tube with distant bracts. Stigma lobes usually forked. Fruit red with purple pulpa.
Hylocereus ocamponis - (incl. Hylocereus guatemalense, Hylocereus purpursii) Mexico & Guatemala. Stems white-waxy, margins horny, spines needle-like, to 12 mm long. Flowers 25–32 cm long with white inner petals. Bracts overlapping, with purple margins.
Hylocereus setaceus - Stems green without horny margins, rather spiny. Flowers 19–22 cm with small tubercles and bracts. Flowers similar to Selenicereus. Fruit red.
Hylocereus stenopterus - Costa Rica. Stems thin, soft, green. Flowers 9–10 cm long, 13–15 cm wide, tube short, tepals purplish red.
Hylocereus triangularis (incl. Hylocereus cubensis). Cuba, Haiti, Dominican Republic, Jamaica. Stems green without horny margins, slender. Flowers ca. 20 cm long, base with wide overlapping scales.
Hylocereus trigonus - (incl. Hylocereus napoleonis, Hylocereus antiguensis). West Indies (Puerto Rico south to Grenada). Stems green without horny margins. Flowers ca. 22 cm long, 21 cm wide, base with small, narrow, widely spaced scales, sometimes spiny. Fruit red.
Hylocereus undatus - Native habitat unknown and maybe of hybrid origin. Stems green, margins undulate and horny. Flowers 25–30 cm long, white with green outer tepals and bracts. Fruit red with white pulpa.