Echinocactus
| Echinocactus | |
|---|---|
| File:Echinocactus platyacanthus.jpg | |
| Kingdom | Plantae |
| Family | Cactaceae |
| Subfamily | Cactoideae |
| Tribe | Cacteae |
| SubTribe | |
| Genus | Echinocactus |
| Species | |
| Notes | Taxonomy follows Joël Lodé (2015). Note: E. grusonii has been moved to Kroenleinia. |
Etymology
Derived from the Greek echinos (hedgehog or sea-urchin), referring to the globose shape of these plants, which are heavily armed with stout spines.
Description
Echinocactus is a genus of large, globose to shortly columnar cacti. They are known for being exceptionally robust, often with flattened apices densely covered in protective wool.
- Stems: Can have up to 60 ribs. The areoles are large and elongated, often becoming confluent (merging) in older specimens. Unlike some related genera, they lack nectar glands.
- Spines: Very stout and strong, with a clear differentiation between central and radial spines.
- Flowers: Diurnal and self-sterile, emerging from the woolly apex. They are typically yellow or pink and bell-shaped. Interestingly, while most are pollinated by bees, some species (like E. horizonthalonius) are reported to be visited by bats.
- Fruits: Globose to elongated, densely covered in scales and wool. They can be fleshy or dry when ripe.
- Seeds: Generally very large and black.
Habitat
Echinocactus species thrive in extremely diverse and harsh environments, from low desert plains at 30 m to mountain woodlands at 2200 m altitude. They grow on limestone, rocky slopes, and mineral-rich sandy soils across the Sonoran and Chihuahuan deserts.
Distribution
- Mexico: Widespread in the northern and central states (Chihuahua, Coahuila, San Luis Potosí, Hidalgo, Zacatecas, etc.).
- USA: Arizona, California, Nevada, New Mexico, Oklahoma, Texas, Utah.
Species
Following the taxonomic revision by Joël Lodé (2014), the genus is restricted to 5 primary species (excluding the former E. grusonii):
- Echinocactus horizonthalonius (Eagle's Claw)
- Echinocactus parryi
- Echinocactus platyacanthus (Giant Visnaga; syn. E. ingens)
- Echinocactus polycephalus
Taxonomy and Evolution
The genus has undergone significant changes due to molecular studies (Bárcenas et al., 2011; Hernández-Hernández et al., 2011):
- Kroenleinia: The famous "Golden Barrel" (*E. grusonii*) was found to be more closely related to Ferocactus and was moved to the genus Kroenleinia by Lodé.
- Polyphyly: Despite looking similar, the genus is polyphyletic. Species like E. polycephalus and E. parryi remain "conflicting taxa" that may require further reassignment.
- Hybrid Origin: Evidence suggests that some species might have a hybrid origin (reticulate evolution) between Ferocactus and Echinocactus lineages.
