Arthrocereus
| Arthrocereus | |
|---|---|
| File:Arthrocereus rondonianus.jpg | |
| Kingdom | Plantae |
| Family | Cactaceae |
| Subfamily | Cactoideae |
| Tribe | Cereeae |
| SubTribe | Trichocereinae |
| Genus | Arthrocereus |
| Species | |
| Notes | Taxonomy follows Joël Lodé (2015). |
Etymology
The name Arthrocereus means "Articulated wax candle". This refers to the first described species (the old type, C. microsphaericus), which has segmented stems, although this characteristic is not shared by the other taxa currently placed in the genus.
Description
Arthrocereus is a genus of solitary or low shrubby plants with cylindrical, non-segmented stems that can be erect or spreading. The areoles are small and close-set, usually bearing many fine, bristle-like spines.
The flowers are nocturnal and subapical, featuring a long funnel-shaped floral tube. Flower colors range from white and pinkish-white to lilac-pink. They are pollinated by moths (Sphingidae). The fruits are spherical and indehiscent, with persistent floral remains. The seeds are egg-shaped, shiny, and blackish-brown. Seed dispersal is carried out by bats, birds, and small terrestrial mammals.
Habitat
The genus grows at altitudes between 450 and 1500 m in dry savannas and rocky areas. They are often found in the shade of shrubs or among grasses, sometimes on ferruginous (iron-rich) soils and frequently near temporary streams.
Distribution
- Brazil (Mato Grosso, Minas Gerais)
Species
According to the Joël Lodé index, the genus currently includes 4 recognized species and 2 subspecies:
- Arthrocereus glaziovii
- Arthrocereus melanurus
- Arthrocereus melanurus subsp. magnus
- Arthrocereus melanurus subsp. estevesii
- Arthrocereus rondonianus
- Arthrocereus spinosissimus
Notes
- There was historical confusion regarding the genus type. Following a proposal by N. Taylor, Arthrocereus glaziovii was established as the new type (neotype) to conserve the genus name.
- While close to Echinopsis s.s., Arthrocereus differs in its general appearance, pollen structure, and its indehiscent fruits.
- Arthrocereus mirabilis is excluded from this genus and is recognized as Setiechinopsis mirabilis.
- The genus is endemic to Brazil and is recognized as correct in major modern taxonomic works, including "The New Cactus Lexicon" and molecular studies by Arakaki and Nyffeler & Eggli.
