Basic Information
Common Name: Southern Tarplant
Scientific Name: Centromadia parryi ssp. australis
Species Code: CENPAR
Management Category: VF (species with limited distribution in the MSPA or needing specific vegetation characteristics requiring management)
Occurrence Map
Table of Occurrences

Goals and Objectives

Goal: Maintain, enhance and restore alkali playa vegetation communities on Conserved Lands in the MSPA that supports or has the potential to support VF species (i.e., Coulter's saltbush, Parish's brittlescale, southern tarplant) so that the vegetation community has high ecological integrity, and these species are resilient to environmental stochasticity, catastrophic disturbances and threats, such as very large wildfires, invasive plants and prolonged drought, and will be likely to persist over the long term (>100 years).

regional and/or local NFO 2018 VF

Management units: 5, 6

In 2018, inspect occurrences of alkali playa MSP VF plant species (i.e., Coulter's saltbush, Parish's brittlescale, southern tarplant) on Conserved Lands using the regional IMG monitoring protocol to record abundance and collect habitat and threat 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 2018 with Management Recommendations 2021
Threat Name Threat Code
Altered hydrologyALTHYD
Human uses of the PreservesHUMUSE
Invasive plantsINVPLA
Urban developmentURBDEV
File name Lead Author Year Type
MSP Roadmap Dec 31, 2016: VF Species and Vegetation Goals, Objectives, and Actions San Diego Management and Monitoring Program 2016 other

Current Distribution Rangewide

Known from Point Conception near Santa Barbara, Ventura, Los Angeles, Orange, and San Diego Counties. Also occurs south into Baja, California Mexico [1].

Known Populations in San Diego County

Known to occur on MU5 (in Ramona and within the Ramona Grasslands), MU6 (San Dieguito Lagoon, Lake Hodges shoreline, Escondido/San Dieguito River Valley), and MU7 (Del Mar and San Dieguito Lagoon Ecological Preserve [2].

List Status

None [1].

Habitat Affinities

Found in vernally wet areas such as along the edges of marshes and vernal pools, often in association with valley and foothill grasslands in areas with poorly drained or alkaline soils and where competition from other plants is limited by alkalinity, seasonal soil saturation, or the effects of human disturbance. Found from 0-480 m (0-1475 ft) in elevation [1].

Taxonomy and Genetics

A member of the Asteraceae (sunflower family), and was previously known as Hemizonia parryi ssp. australis [3]. The species was first described in 1864 by Greene as Hemizonia parryi [4]. The subspecies australis was first described in 1935 by David Keck based on a specimen he collected in Seal Beach [5]. In 1999 the genus Centromadia was applied to accommodate the tarplants (Hemizonia ssp.) commonly referred to as spikeweeds, which are distinguished from other tarplants by the presence of spine tipped leaves, giving it the name Centromadia parryi ssp. australis [4]. The species description and naturally restricted distribution has remained the same during the changes in nomenclature. Chromosomes: 2n=22 [3].

Life History Demography

Annual herb with erect stems and soft to coarsely hairy spine-tipped leaves [3]. The dark green leaves and bracts are densely covered with yellow stalked glands. Mature plants are 2.5-76.2 cm (1-30 in) tall [6]. The flowering heads are 2.5-6 mm (0.1-0.2 in) subtended by spine tipped bracts and found at the end of soft hairy stalks. Bracts do not exceed the flowering head [3].

Seasonal Phenology

Yellow ray flowers with black anthers and yellow-orange disk flowers with red to dark purple anthers [3]. Flowering heads often fade to orange with age [4]. Blooms from May to November [1].

Pollination Seed Dispersal

Seeds fall beneath the parent plant in tumbleweed-like clusters that are dispersed by wind or by sticking to animals fur as they pass by [6]. Seeds are also eaten by birds and small mammals which act as dispersal agents as they move around a foraging area. Potential pollinators such as bees, wasps, flies, and beetles have been observed visiting flower heads.


Threatened by habitat fragmentation as a result of urbanization and development, vehicular and foot traffic, grazing, competition from non-native plants and alterations to the watersheds that support the seasonal wetlands they occur in [1, 7].

Special Considerations:

Numbers of individuals can vary widely at a given location from year to year, depending on recent disturbance and seasonal precipitation [7]. Sterile hybrids with Deinandra fasciculata documented [3].

Literature Sources

[1] California Native Plant Society Rare Plant Program. 2017. Inventory of Rare and Endangered Plants (online edition, v8-02). California Native Plant [Society, Sacramento, CA. Available: Accessed: February 15, 2017.

[2] MSP-MOM. 2014. Management Strategic Plan Master Occurrence Matrix. San Diego, CA. Available:

[3] Baldwin, B.G. 2017. Centromadia parryi subsp. australis, in Jepson Flora Project (eds.) Jepson eFlora. Available: Accessed February 20, 2017.

[4] Baldwin, B.G. 1999. New Combinations and New Genera in the North American Tarweeds (Compositae-Madiinae). Novon 9(4): 462-471.

[5] Keck, D.D. 1935. Studies Upon the Taxonomy of the Madinae. Madroño 3(1): 4-18.

[6] Cheadle Center for Biodiversity and Ecological Restoration. 2011. Southern Tarplant Education pamphlet. Available:

[7] City of Huntington Beach. 2016. General Plan Update. City of Huntington Beach Planning and Building Department. Huntington Beach, California.