Home/Species/ Rincon Mountain Rockcress

Pennellia tricornuta

(Rollins) R.A. Price, C.D. Bailey & Al-Shehbaz

Rincon Mountain Rockcress

G2Imperiled Found in 1 roadless area NatureServe Explorer →

G2ImperiledGlobal Rank

UnknownThreat Impact

Identity

Unique IDELEMENT_GLOBAL.2.139715

Element CodePDBRA06200

Record TypeSPECIES

ClassificationSpecies

Classification StatusStandard

Name CategoryVascular Plant

Endemicendemic to a single state or province

KingdomPlantae

PhylumAnthophyta

ClassDicotyledoneae

OrderCapparales

FamilyBrassicaceae

GenusPennellia

Synonyms

Arabis tricornutaRollins

Other Common Names

Chiricahua Rockcress (EN)

Concept Reference

Kartesz, 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.

Taxonomic Comments

According to FNA (2010), Pennellia tricornuta "was recognized by R. C. Rollins (1941, 1993) under Arabis, but as shown by Price, Bailey & Al-Shehbaz and by S. Fuentes-Soriano (2004), it clearly belongs to Pennellia."

Conservation Status

Rank Method Rank calculation - Biotics v2

Review Date2026-03-12

Change Date2026-03-12

Edition Date2026-03-12

Edition AuthorsMaybury, K. (reviewed by S. Schwartz) (1996), rev. S. Schuetze 7/2011, rev. Soteropoulos (2026)

Threat ImpactUnknown

Range Extent1000-5000 square km (about 400-2000 square miles)

Number of Occurrences6 - 20

Rank Reasons

Pennellia tricornuta is a perennial herb found on steep and rocky slopes, under pines in Madrean evergreen woodland and Madrean conifer forest, and on road banks and sand banks. It is endemic to the southwestern United States in southeastern Arizona, in the Chiricahua, Huachuca, Rincon, and Tucson mountains. There are ten estimated occurrences, which potentially face threats from wild fires and recreational activities. The Horseshoe2 fire in 2011 spread through a large portion of this species' habitat in the Chiricahua Mountains, and field surveys are needed to determine the impacts to this species. Several occurrences are considered historical, and monitoring of populations should be conducted to improve our understanding of reproduction, plant abundance, threats, and trends, as well as continuing conservation measures to protect the taxon.

Range Extent Comments

Pennellia tricornuta is endemic to the southwestern United States in southeastern Arizona, in the Chiricahua and Huachuca mountains in Cochise County, the Santa Rita Mountains in Santa Cruz County, and the Rincon and Tucson mountains in Pima County (ARPC 2001, FNA 2010, AZNHP 2019). Range extent was estimated to be 4513 square kilometers using NatureServe Network occurrence data documented between 1994 and 2025 (AZGFD 2025, RARECAT 2025).

Occurrences Comments

By applying a 1 km separation distance to NatureServe Network occurrence data documented between 1994 and 2025, it is estimated that there are ten occurrences rangewide (AZGFD 2025, RARECAT 2025). Several occurrences are considered historic, last observed over 30 years ago, and fieldwork is needed to determine if they are extant, especially within the Santa Rita and Rincon mountains (AZNHP 2019).

Threat Impact Comments

A fire may have spread through a large portion of habitat in the Chiricahua Mountains (Horseshoe2 fire, May-June 2011), but the severity of this fire is unknown (AZNHP 2019). This species is potentially threatened by future wildfires and recreational activities (AZGFD 2025).

Ecology & Habitat

Habitat

Pennellia tricornuta grows on steep and rocky slopes, under pines in Madrean evergreen woodland and Madrean conifer forest, and on road banks and sand banks (ARPC 2001, FNA 2010, AZNHP 2019).

Reproduction

This taxon flowers from July to September (FNA 2010).

Terrestrial Habitats

Forest/WoodlandForest - ConiferForest EdgeWoodland - Conifer

Other Nations (1)

United StatesN1

Province	Rank	Native
Arizona	S2	Yes

Threat Assessments

Threat	Scope	Severity	Timing
6 - Human intrusions & disturbance	Restricted (11-30%)	Unknown	Moderate (short-term)
6.1 - Recreational activities	Restricted (11-30%)	Unknown	Moderate (short-term)
7 - Natural system modifications	Large - restricted	Unknown	Unknown
7.1 - Fire & fire suppression	Large - restricted	Unknown	Unknown

Plant Characteristics

DurationPERENNIAL

Economic Value (Genus)No

Roadless Areas (1)

Arizona (1)

Area	Forest	Acres
Lower Rincon	Coronado National Forest	3,278

References (7)

Arizona Game and Fish Department (AZGFD). 2025. Data export from Biodiversity Tracking and Conservation System (Biotics 5). Arizona Game and Fish Department, Phoenix, AZ (accessed 19 Dec 2025).
Arizona Natural Heritage Program (AZNHP). 2019. Element Subnational Ranking Form: <i>Pennellia tricornuta</i> in Biotics 5 database. NatureServe, Arlington, Virginia (accessed 12 Mar 2026).
Arizona Rare Plant Committee (ARPC). 2001. Arizona rare plant field guide: A collaboration of agencies and organizations. Arizona Rare Plant Committee, Phoenix.
Flora of North America Editorial Committee (FNA). 2010. Flora of North America north of Mexico. Vol. 7. Magnoliophyta: Salicaceae to Brassicaceae. Oxford University Press, New York. xxii + 797 pp.
Kartesz, 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.
Kearney, T.H., R.H. Peebles, and collaborators. 1951. Arizona flora. 2nd edition with Supplement (1960) by J.T. Howell, E. McClintock, and collaborators. Univ. California Press, Berkeley. 1085 pp.
Rollins, R.C. 1993a. The Cruciferae of continental North America: Systematics of the mustard family from the Arctic to Panama. Stanford Univ. Press, Stanford, California. 976 pp.

Pennellia tricornuta

Habitat

Reproduction

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