Heliocereus
| Heliocereus | |
|---|---|
| File:Heliocereus speciosus.jpg | |
| Kingdom | Plantae |
| Family | Cactaceae |
| Subfamily | Cactoideae |
| Tribe | Phyllocacteae |
| SubTribe | Hylocereinae |
| Genus | Heliocereus |
| Species | |
| Notes | Taxonomy follows Joël Lodé (2015). Lodé maintains Heliocereus as a distinct genus within the Hylocereinae subtribe. |
Etymology
The name is derived from the Greek helios (sun) and the Latin cereus (wax candle), referring to the diurnal (day-blooming) nature of its spectacular, sun-loving flowers.
Description
Heliocereus consists of semi-epiphytic, lithophytic, or sprawling terrestrial cacti with slender, ribbed stems.
- Stems: Typically possess 3 to 7 prominent, acute ribs. They are more robust and more heavily spined than the flattened stems of Disocactus.
- Flowers: Large, diurnal, and funnel-shaped. They are predominantly brilliant scarlet or crimson, often displaying a metallic blue or violet iridescence on the inner petals. The floral tube is relatively short and bears small scales and hairs.
- Fruits: Globose to ovoid, fleshy, and reddish when mature. They are covered with small scales and occasional bristles.
- Seeds: Relatively large, black, and pitted (foveolate).
Habitat
The genus typically grows in oak and pine-oak cloud forests, frequently as a lithophyte on rocky cliffs or occasionally as an epiphyte on trees. They are adapted to higher altitudes, usually between 1500 m and 2700 m.
Distribution
- Mexico: Central and southern states (Chiapas, Guerrero, Jalisco, Michoacán, Morelos, Oaxaca, Puebla, Veracruz).
- Central America: Guatemala, El Salvador, Honduras, Nicaragua.
Species and Subspecies
According to Lodé (2015), the genus includes 3 recognized species and 2 subspecies:
- Heliocereus aurantiacus
- Heliocereus cinnabarinus
- Heliocereus speciosus
- Heliocereus speciosus subsp. amecamensis (Distinctive white-flowered subspecies)
- Heliocereus speciosus subsp. blomianus
Taxonomy
While many modern systems merge Heliocereus into Disocactus, Lodé (2015) maintains it as a separate genus. He argues that its more primitive floral structure, diurnal blooming habit (pollinated by hummingbirds), and strongly ribbed, spiny stems justify its independence from the more specialized, often spineless and flattened-stemmed Disocactus.
