Taxon Report

Deinandra conjugens (Keck) B.G. Baldwin

Otay tarplant

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Taxon Summary

Deinandra conjugens, commonly known as Otay tarplant, is a annual herb in the Asteraceae that is found in California and elsewhere. It occurs within Coastal scrub, and Valley and foothill grassland, growing at elevations from 25 to 300 meters. Deinandra conjugens is ranked 1B.1, Plants Rare, Threatened or Endangered in California and Elsewhere; Seriously threatened in California.


  Classification

Scientific Name:
Deinandra conjugens (Keck) B.G. Baldwin
Common Name:
Otay tarplant
Family: Asteraceae
Element Code: PDAST4R070
USDA Plants Symbol: DECO13
Synonyms/Other Names:
  • Hemizonia conjugens Keck

Ecology and Life History

Lifeform: annual herb
Blooming Period: (Apr)May-Jun (Apr)May-Jun
Elevation: 25-300 (80-985)
General Habitats: Coastal scrub, Valley and foothill grassland
Microhabitat: Clay
Microhabitat Details:

Occurrence Data from the CNDDB

Total Occurrences: 42
Element Occurrence Ranks:
   Excellent (A) 0
   Good (B) 11
   Fair (C) 7
   Poor (D) 5
   None (X) 0
   Unknown (U) 19
California Endemic:  False
California Counties and Islands: Name (Code)
San Diego (SDG)
Quads: Name (Quad Code)
Dulzura (3211667), Imperial Beach (3211751), Jamul Mountains (3211668), National City (3211761), Otay Mesa (3211658)

Threat List Data from the CNDDB

Threat List Total: 14
EOs with Threat Listed: Total EOs % of EOs
34 81 %
Non-native plant impacts 25 59%
Development 21 50%
Foot traffic/trampling 15 35%
Road/trail construction/maint. 15 35%
Vandalism/dumping/litter 13 30%
ORV activity 12 28%
Erosion/runoff 10 23%
Wood cutting or brush clearing 7 16%
Other 5 11%
Improper burning regime 3 7%
Altered flood/tidal/hydrologic regime 2 4%
Recreational use (non-ORV) 2 4%
Grazing 2 4%
Non-native animal impacts 1 2%

Notes

Threatened by development, agriculture, vehicles, illegal dumping, foot traffic, non-native plants, habitat disturbance, and Border Patrol activities. Possibly threatened by landfill construction. Known in BA from only one occurrence. State and federally listed as Hemizonia conjugens; see this name in The Jepson Manual. See Aliso 4(1):109 (1958) for original description, MadroƱo 25(3):159 (1978) for information on distribution and taxonomy, and Novon 9:462-471 (1999) for revised nomenclature.
Threats:
Taxonomy:
Citation California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 5 February 2025].