ITIS Basic Information
Common Name: Parry's Tetracoccus
Scientific Name: Tetracoccus dioicus
Species Code: TETDIO
Management Category: SS (species not considered at risk of loss but still requires management)
Occurrence Map

Historically present
Currently present
Currently not detected
Table of Occurrences
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Species Information

MSP Species Background

Goals and Objectives

Goal: Maintain or enhance existing Parry's tetracoccus occurrences to ensure multiple conserved occurrences with self sustaining populations to increase resilience to environmental and demographic stochasticity, maintain genetic diversity, and ensure persistence over the long term (>100 years) in chaparral and coastal sage scrub vegetation communities.

regional and/or local NFO 2019 SS
MON-IMP-IMG TETDIO-1

Management units: 3, 8

In 2019, inspect Parry's tetracoccus occurrences on Conserved Lands (see occurrence table) using the regional rare plant IMG monitoring protocol to record abundance and collect habitat and threats covariate data to determine management needs.

Action Statement Action status Projects
IMP-1 Based upon occurrence status and threats, determine management needs including whether routine management or more intensive management is warranted. on hold
IMP-2 Submit project metadata, monitoring datasets and management recommendations to the MSP Web Portal. on hold
Criteria Deadline year
Surveys Completed in 2019 with Management Recommendations 2021
Threat Name Threat Code
Human uses of the PreservesHUMUSE
Invasive plantsINVPLA
Urban developmentURBDEV
Code Obj. code Statement
TETDIO-2 MGT-IMP-IMG Beginning in 2020, conduct routine management actions identified through the 2019 IMG monitoring at Parry's tetracoccus occurrences on Conserved Lands (see occurrence table). Depending on the type and level of threat, management should be conducted as needed, not necessarily every year, and using BMPs with precautions to do no harm.
local NFO 2020, 2021 SS
MGT-IMP-IMG TETDIO-2

Management units: 3, 8

Beginning in 2020, conduct routine management actions identified through the 2019 IMG monitoring at Parry's tetracoccus occurrences on Conserved Lands (see occurrence table). Depending on the type and level of threat, management should be conducted as needed, not necessarily every year, and using BMPs with precautions to do no harm.

Action Statement Action status Projects
IMP-1 Perform routine management activities such as protecting occurrences from disturbance through fencing and enforcement and controlling invasive non-native plant species to less than 20% absolute cover. On hold
IMP-2 Submit project metadata and management data to the MSP Web Portal. On hold
Criteria Deadline year
Routine Management Completed as Needed Based Upon Monitoring Recommendations 2021
Threat Name Threat Code
Human uses of the PreservesHUMUSE
Invasive plantsINVPLA
Urban developmentURBDEV
Code Obj. code Statement
TETDIO-1 MON-IMP-IMG In 2019, inspect Parry's tetracoccus occurrences on Conserved Lands (see occurrence table) using the regional rare plant IMG monitoring protocol to record abundance and collect habitat and threats covariate data to determine management needs.
Regional NFO 2017 SS
MON-RES-SPEC TETDIO-3

Management units: 3, 8

In 2017, begin field research into soils and habitat relationships and conduct habitat suitability and climate change modeling for Parry's tetracoccus and other edaphic endemic plants to better understand habitat requirements and to identify and prioritize geographic areas important for connectivity, restoration, and range shifts due to climate change and other threats.

Action Statement Action status Projects
RES-1 Test soils at potential expansion sites and compare to occupied reference sites to determine site suitability based on soils. In progress Enhancing the Resilience of Edaphic Endemic Plants
RES-2 Prepare habitat suitability models under current environmental conditions and for different scenarios of climate change to delineate potential future habitat. In progress Enhancing the Resilience of Edaphic Endemic Plants
RES-3 Collect covariate data on vegetation composition and cover (alliance and association-level mapping), soils, invasive plants and other threats for selected populations. In progress Enhancing the Resilience of Edaphic Endemic Plants
RES-4 Prioritize locations for conservation, management, and future surveys based on predicted distributions and environmental correlates. In progress Enhancing the Resilience of Edaphic Endemic Plants
RES-5 Submit project metadata, monitoring data, habitat models, analyses, and report to MSP web portal. In progress Enhancing the Resilience of Edaphic Endemic Plants
Criteria Deadline year
Refined Models and Prioritized Future Survey Locations for Parry's Tetracoccus by 2018 2021
Threat Name Threat Code
Climate changeCLICHN
Invasive plantsINVPLA
Loss of connectivityLOSCON
Urban developmentURBDEV
Code Obj. code Statement
TETDIO-1 MON-IMP-IMG In 2019, inspect Parry's tetracoccus occurrences on Conserved Lands (see occurrence table) using the regional rare plant IMG monitoring protocol to record abundance and collect habitat and threats covariate data to determine management needs.
Covered and Invasive Species Management: Crestridge Ecological Reserve and South Crest Properties
This was a two year, TransNet-funded study (#5001586) on Crestridge Ecological Reserve and South Crest properties. Both properties support MSCP covered species and sensitive habitats, and function as critical landscape linkages between the northern and southern MSCP. Surrounded by residential development and heavily impacted by the 2003 Cedar Fire, these properties are subject to ongoing invasive plant issues. Specific task actions included invasive plant and covered plant species mapping and risk assessment s, invasive plant control and experimental studies, and development of an early detection invasive control plan. This project was partially funded by SANDAG TransNet EMP Land Management Grant #5001586.
Enhancing the Resilience of Edaphic Endemic Plants
The Management Strategic Plan for San Diego County requires prioritization and management for edaphic endemic plants, including the five rare plants addressed in this study. These species face low genetic diversity due to reduced population sizes, geographic isolation, and loss of pollinators. To enhance the resilience of these species across their ranges, we must manage threats to increase population sizes, identify potentially suitable habitat to connect existing populations, find or restore new populations, and provide opportunities for shifting distributions due to climate change. This study identifies and describes geographic areas that support the five edaphic endemic species and their habitat in a design that enhances resilience and provides opportunities for shifting distributions. We developed conceptual models to inform field studies and management, refined soils and vegetation attributes, and assessed regional population structure and threats. We used results to suggest prioritized locations for surveys, management, potential translocation, and additional conservation or acquisition. Project partners (U.S. Geological Survey and San Diego Management and Monitoring Program) modeled suitable habitat for the target species under current and future climate scenarios; we reference models as appropriate.
Valley Fire Rare Plant Discovery Surveys
A project between the SDMMP and US Forest Service to establish and prioritize survey areas on Conserved Lands within the perimeter of the 2020 Valley Fire to document whether historic occurrences are extant and to discover new occurrences for 18 rare plant species. In 2022, AECOM and Conservation Biology Institute botanists surveyed areas for 18 target rare plant species and mapped the spatial extent of each new occurrence, counted or estimated the occurrence population size, and collected voucher specimens. They also photographed each new occurrence from a georeferenced location that captured a representative view of the occurrence. Botanists created a species list for the areas surveyed within the Valley Fire footprint. These areas included locations where rare plants were detected and mapped and negative data point areas where rare plants were not detected. In 2023, botanists shall again conduct surveys on suitable habitat on USFS lands burned in the 2020 Valley Fire. Results from these surveys should lead to a greater understanding of post-fire rare plant composition. In 2023, botanists may see species that did not emerge in the first year of surveys, and species found in the first year of surveys may have expanded their range. The 18 rare plant species included in the surveys are: San Diego thornmint (Acanthomintha ilicifolia), Marvin's allium (Allium marvinii), Western spleenwort (Asplenium vespertinum), Deane's milkvetch (Astragalus deanei), Encinitas baccharis (Baccharis vanessae), San Diego goldenstar (Bloomeria clevelandii), Orcutt's brodiaea (Brodiaea orcuttii), Lakeside ceanothus (Ceanothus cyaneus), San Miguel savory (Clinopodium chandleri), Variegated dudleya (Dudleya variegata), Mission Canyon bluecup (Githopsis diffusa filicaulis), Ramona horkelia (Horkelia truncata), Heart-leaved pitcher sage (Lepechinia cardiophylla), Felt-leaved pitcher sage (Monardella hypoleuca lanata), Chaparral nolina (Nolina cismontana), Gander's ragwort (Packera ganderi), Moreno currant (Ribes canthariforme), and Parry's tetracoccus (Tetracoccus dioicus).

Current Distribution Rangewide

Coastal southern California from Peninsular Range foothills of Orange, Riverside, and San Diego Counties to Baja California, Mexico [1,2].

Known Populations in San Diego County

Eight occurrences on Conserved lands in MUs 3 (South Crest, McGinty Mountain, Sycuan Peak Ecological Reserve), 6 (San Marcos Mountains) and 8 (Merriam Mountains, Monserate Mountain, Wilderness Gardens).

List Status

None [2].

Habitat Affinities

Occurs on dry, stony slopes composed of gabbro-derived soils in chaparral and coastal scrub communities[3; cited from 4]. Elevation range is 165-1,000 meters [2]. Low-growing chamise chaparral, with moderately dense canopy cover [5].

Taxonomy and Genetics

Picrodendraceae family [2].

Life History Demography

Perennial deciduous shrub [2].

Seasonal Phenology

Blooms April to May [2].

Threats

Threatened by agriculture and development [2].

Literature Sources

[1] Webster, G. L. 2016. “Tetracoccus Dioicus.” Jepson eFlora. http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=46211.

[2] CNPS, Rare Plant Program. 2016. Inventory of Rare and Endangered Plants (online edition, v8-02). California Native Plant Society, Sacramento, CA. http://www.rareplants.cnps.org, accessed 29 August 2016.

[3] California Native Plant Society. 2001. Inventory of Rare and Endangered Plants of California (Sixth Edition). Edited by Rare Plant Scientific Advisory Committee David P. Tibor Convening Editor. 6th ed. Sacramento, CA.

[4] Gibson, C. E. 2003. “Viability Assessment: Tetracoccus Dioicus Parry.”

[5] San Diego County Water Authority, Sweetwater Authority, Helix Water District, City of Poway Public Works Department, and Santa Fe Irrigation District. 2015. “Final Mitigated Negative Declaration and Initial Study/ Environmental Checklist Application of Copper-Based Algaecides at Five Reservoirs San Diego County California.”