Pterocactus
| Pterocactus | |
|---|---|
| File:Pterocactus tuberosus.jpg | |
| Kingdom | Plantae |
| Family | Cactaceae |
| Subfamily | Opuntioideae |
| Tribe | Tephrocacteae |
| SubTribe | |
| Genus | Pterocactus |
| Species | |
| Notes | Taxonomy follows Joël Lodé (2015). The genus is accepted as distinct and monophyletic. |
Etymology
The name means "winged cactus", referring to the characteristic winged seeds.
Description
Pterocactus is a genus of geophytic dwarf cacti with tuberous roots.
- Habit: Small, geophytic plants with large underground tuberous roots.
- Stems: Segmented, globose to cylindrical, often papillose; easily detached and capable of rooting; often disappearing during dry periods.
- Areoles: With spines; glochids may be present or absent depending on species.
- Spines: Fine, acicular or subulate, sometimes papery.
- Leaves: Very small, early deciduous.
- Flowers: Diurnal, rotate, yellow to reddish or brownish; emerging from stem tips; stamens sensitive to touch.
- Fruits: Dry, capsule-like, with lateral dehiscence, densely spiny.
- Seeds: Large, pale, with a characteristic papery wing, adapted for wind dispersal.
Habitat
The genus grows in arid and semi-arid environments, including sandy or clayey soils, rocky slopes, and coastal areas.
Altitude range: from sea level up to about 3050 m.
Species are adapted to harsh climates and may tolerate severe frost.
Distribution
- South America:
Argentina (wide distribution), Chile (Aisén region)
Taxonomy
The genus Pterocactus was established by Schumann (1897).
Its validity has never been seriously questioned due to its highly distinctive winged seeds.
Phylogenetic and anatomical studies (Stuppy 2002; Wallace & Dickie 2002; Griffith & Porter 2009; Ritz et al. 2012) confirm that Pterocactus forms a well-defined, monophyletic lineage.
It is placed within the tribe Tephrocacteae, together with genera such as Tephrocactus, Maihueniopsis, Cumulopuntia, and Austrocylindropuntia.
Species
Following the classification of Joël Lodé (2015).
- Pterocactus araucanus
- Pterocactus australis
- Pterocactus fischeri
- Pterocactus gonjianii
- Pterocactus hickenii
- Pterocactus megliolii
- Pterocactus reticulatus
- Pterocactus tuberosus
- Pterocactus valentinus
Notes
- The winged seeds are unique within the subfamily and a key diagnostic feature.
- The plants are geophytes, with above-ground parts often disappearing seasonally.
- Former synonyms such as P. decipiens and P. kuntzei are included within P. tuberosus.
