(Engelm.) L. Benson
Identity
Unique IDELEMENT_GLOBAL.2.132964
Element CodePDCAC0E060
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
IUCNLeast concern
CITESAppendix I
Endemicendemic to a single nation
KingdomPlantae
PhylumAnthophyta
ClassDicotyledoneae
OrderCaryophyllales
FamilyCactaceae
GenusPediocactus
SynonymsUtahia sileri(Engelm.) Britt. & Rose
Other Common NamesSiler pincushion cactus (EN)
Concept ReferenceKartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2024-05-23
Change Date2013-09-16
Edition Date2024-05-23
Edition AuthorsD. Atwood, rev. C. Russell, rev. Maybury (1996), rev. S. Schuetze (2012), rev. A. Tomaino (2013), rev. N. Ventrella (2024)
Threat ImpactHigh - medium
Range Extent1000-5000 square km (about 400-2000 square miles)
Number of Occurrences6 - 20
Rank ReasonsPediocactus sileri is endemic to a narrow strip along the Arizona-Utah border, where it is ecologically restricted to gypsum and salt-rich soils derived from the Moenkopi formation. The majority of populations occur on Bureau of Land Management lands in the Arizona Strip and Cedar City Districts, which have documented plants occurring on 17,000 ha of land. In most cases individual plants are widely separated, but the survey did find three dense populations. Fairly heavy off-road vehicle use has adversely impacted some populations. Other threats include livestock grazing and long-term drought. Many populations in long-term monitoring plots are in decline in recent years due to drought and herbivory.
Range Extent CommentsPediocactus sileri occurs in western North America, where it is found along the Utah-Arizona border in Coconino and Mohave counties, Arizona and in Washington and Kane counties, Utah in the United States (USFWS 2008). Specifically, this species occurs from just southeast of St. George, Utah onto the Uinkaret Plateau south of Colorado City, Arizona and then northeast towards Fredonia, Arizona (Skillin 2021). Range extent was estimated using herbarium specimens, NatureServe Network occurrence data, and data from the Utah Rare Plant Database collected between 1993 and 2022 (UNHP 2021, NatureServe 2024, SEINet 2024).
Occurrences CommentsBy applying a 2 km separation distance to population location data from the Utah Rare Plant Database, herbarium specimens, and NatureServe Network occurrence data documented between 1993 and 2022, there are thirteen estimated occurrences (UNHP 2021, NatureServe 2024, SEINet 2024).
Threat Impact CommentsIllegal poaching of this cactus from the wild by collectors seems to be a low concern to this species, due to the difficulty in keeping this cactus alive in cultivation, and there is no current evidence of poaching, though plants have sometimes disappeared without apparent cause (Skillin 2021). Off-road vehicle use and impacts from recreation activities have impacted Pediocactus sileri, especially in habitat near population centers around St. George, Utah and Fredonia, Arizona. Uranium mining was a potential threat to this species in the past (USFWS 2008), but has decreased due to the 2012 Secretary of the Interior's decision to withdraw more than a million acres of land from mineral mining, which includes Pediocactus sileri habitat (USFWS 2018). Gypsum mining and oil and gas exploration and development are currently considered to be low threats, but there is the potential for these threats to increase depending on future markets (USFWS 2008). Other possible future threats include increased urban development in Utah and a proposed Lake Powell water pipeline that would cross BLM-lands in the Arizona strip region (USFWS 2018). Predation by larvae of the cactus borer beetle and by native rodents has impacted individuals and remains a significant threat to this species along with drought (USFWS 2018).