Stephanocereus
From M&J Cactus Wiki
| Stephanocereus | |
|---|---|
| File:Stephanocereus leucostele.jpg | |
| Kingdom | Plantae |
| Family | Cactaceae |
| Subfamily | Cactoideae |
| Tribe | Cereeae |
| SubTribe | |
| Genus | Stephanocereus |
| Species | |
| Notes | Taxonomy follows Joël Lodé (2015) with molecular insights from Machado et al. (2006). The genus is monotypic and phylogenetically complex. |
Etymology
The name means "crowned Cereus", referring to the characteristic annular cephalium.
Description
Stephanocereus is a monotypic genus of columnar cacti with a distinctive ring-like cephalium.
- Habit: Columnar, mostly solitary, rarely branched; reaching 2–5 m in height.
- Stems: Bluish-green, irregularly segmented with growth; 13–18 straight ribs.
- Areoles: Close-set, strongly woolly.
- Spines: Numerous (≈20) short white radial spines; 1–2 longer, stiffer central spines, golden-yellow.
- Cephalium: Annular (ring-shaped), densely woolly and hairy.
- Flowers: Nocturnal, tubular to campanulate, creamy-white; appearing laterally on both current and older cephalia; possibly self-fertile.
- Pollination: Primarily by bats; also visited by hymenopterans.
- Fruits: Elongated, thick-walled; bluish and waxy when ripe; pulp white or red.
- Seeds: Black, warty, dull; with mucilaginous coating.
- Dispersal: By bats and ants.
Habitat
Endemic to Brazilian semi-arid environments:
- rocky outcrops, crevices and quartz sands
- among grasses and shrubs
- caatinga vegetation
Altitude range: approximately 270–750 m.
Distribution
Endemic to Brazil:
- Bahia
Taxonomy
The genus is currently accepted but phylogenetically complex.
Key points:
- Berger (1926): established the genus
- Machado et al. (2006): indicated polyphyly among related genera (including Arrojadoa and Pilosocereus)
- Close relationship with Arrojadoa suggested, but differing pollination syndromes and morphology
Important considerations:
- Stephanocereus leucostele is the only species clearly belonging to the genus
- Other taxa (e.g. S. luetzelburgii) are likely unrelated and closer to other genera
- Some authors propose splitting related lineages into separate monotypic genera
The genus is therefore maintained as distinct and monotypic.
Species
Currently one recognized species:
Notes
- Characterized by its unique annular cephalium.
- Represents a highly specialized evolutionary lineage.
- Pollination biology differs from closely related genera.
- Likely part of a complex evolutionary network involving reticulate evolution.
