Disocactus
| Disocactus | |
|---|---|
| File:Disocactus phyllanthoides.jpg | |
| Kingdom | Plantae |
| Family | Cactaceae |
| Subfamily | Cactoideae |
| Tribe | Phyllocacteae |
| SubTribe | Hylocereinae |
| Genus | Disocactus |
| Species | |
| Notes | Taxonomy follows Joël Lodé (2015). Not to be confused with the terrestrial genus Discocactus. |
Etymology
The name is derived from the Greek dis (twice) and refers to the equal length of the inner and outer flower segments, a distinguishing feature of the genus as originally described.
Description
Disocactus is a genus of epiphytic or lithophytic cacti (growing on trees or rocks). They possess either ribbed or flattened stems known as **phylloclades**. Spines are usually minimal, setose (bristle-like), or entirely absent, while areoles are often numerous along the stem margins.
- Flowers: Typically diurnal (day-blooming) and self-sterile. Most species are pollinated by hummingbirds. The flowers are large and come in various shapes (funnel-shaped, tubular, or rarely rotate), with colors ranging from white and pink to deep red or purple. A key feature is that the stamens are arranged in two distinct series.
- Fruits: Small, berry-like fruits that are mostly naked or have very few scales.
- Seeds: Ovate, black or brown, and covered in a mucilaginous envelope which aids in dispersal in tropical environments.
Habitat
These cacti are found in the tropical cloud forests of Southern Mexico and Central America. They grow as epiphytes in high-humidity environments at altitudes ranging from 700 m to 2100 m.
Distribution
- Mexico: Chiapas, Colima, Durango, Guerrero, Jalisco, Mexico D.F., Michoacán, Morelos, Nayarit, Oaxaca, Sinaloa, Veracruz.
- Central America: El Salvador, Guatemala, Honduras, Nicaragua.
Species
Following the strict circumscription of Joël Lodé (excluding Aporocactus and Heliocereus), the genus contains 8 recognized species:
- Disocactus ackermannii
- Disocactus biformis
- Disocactus eichlamii
- Disocactus macdougallii
- Disocactus macranthus
- Disocactus nelsonii
- Disocactus phyllanthoides
- Disocactus quetzaltecus
Taxonomy and Comments
The classification of Disocactus has been a subject of intense debate among botanists like Kimnach, Barthlott, and Hunt.
- Current Status: Joël Lodé follows the molecular evidence suggesting that Disocactus s.l. is polyphyletic. Consequently, he maintains Aporocactus and Heliocereus as separate genera based on the characteristics of their floral receptacles.
- Reassignments:
- D. flagelliformis and D. martianus are moved to Aporocactus.
- D. speciosus and the recently described D. lodei are moved to Heliocereus.
- D. amazonicus is reassigned to Pseudorhipsalis.
- D. testudo and D. wittii are moved back to Strophocactus.
