Geohintonia
| Geohintonia | |
|---|---|
| File:Geohintonia mexicana.jpg | |
| Kingdom | Plantae |
| Family | Cactaceae |
| Subfamily | Cactoideae |
| Tribe | Cacteae |
| SubTribe | |
| Genus | Geohintonia |
| Species | |
| Notes | Taxonomy follows Joël Lodé (2015). A monotypic genus, closely related to Aztekium. |
Etymology
The genus is named in honor of George S. Hinton (1949–), a Mexican farmer and plant collector who discovered the plant in 1991.
Description
Geohintonia is a monotypic genus consisting of a single species, G. mexicana. It is a slow-growing, globose cactus.
- Stems: Solitary, globose to somewhat columnar with age, reaching up to 10 cm in height and diameter. The epidermis is a distinct glaucous (grey-green) color and covered with a fine pruinose coating.
- Ribs: Numerous (usually 18–20), well-defined, and acute.
- Areoles and Spines: Areoles are small and initially woolly; spines are few, short, weak, and often deciduous (falling off with age).
- Flowers: Diurnal and self-sterile, appearing at the apex. They are funnel-shaped and bright pink to magenta.
- Fruits: Small, ovoid, and hidden in the apical wool. They are thin-walled and dehisce (open) irregularly.
- Seeds: Small, black, and shiny with a finely tuberculate surface.
Habitat
The genus is an extreme specialist, growing exclusively on vertical gypsum cliffs in a very restricted area. It is found at altitudes around 1100–1200 m, often growing alongside Aztekium hintonii.
Distribution
- Mexico: Endemic to a single location in the state of Nuevo León (Galeana).
Species
According to Lodé (2015), the genus consists of only one species:
- Geohintonia mexicana (Type species)
Taxonomy
Molecular evidence confirms that Geohintonia is closely related to Aztekium, but it is maintained as a separate genus due to its distinct morphological features, such as the absence of secondary ribs (intercostal furrows) and its unique seed structure.
