CPC Plant Profile: Yreka Phlox
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Plant Profile

Yreka Phlox (Phlox hirsuta)

Flowers of Phlox hirsuta Photo Credit: © 2005 Dean Wm. Taylor
Description
  • Global Rank: G1 - Critically Imperiled
  • Legal Status: Federally Endangered
  • Family: Polemoniaceae
  • State: CA
  • Nature Serve ID: 130294
  • Date Inducted in National Collection: 09/28/2021

Yreka phlox is a narrow endemic perennial plant with pink to white flowers. Its found only in the area of the city of Yreka, in extreme northern California. It grows from two to six inches tall, though stems growing along the ground can be longer. The stems are densely hairy (hirsute). The plants at the five extant locations vary in number from 200 to 10,000 plants on both private and public lands. (Recovery Plan)

Participating Institutions
Updates
  • 09/23/2020
  • Propagation Research

Ongoing research indicates that P. hirsuta does not self-pollinate and relies on insects to vector pollen to set fruit and produce seed (Ferguson 2004). Seed set in a subsample of P. hirsuta plants ranged between 78 and 92 percent and seed viability was recorded as high as 84 percent (Ferguson 2004, Ferguson and Filipski 2005). Of viable seeds that were planted in pots in the laboratory, 68.5 percent produced viable seedlings. Seedlings raised in a greenhouse took 4 to 22 days to emerge from the soil (Ferguson and Filipski 2005).

  • 09/23/2020
  • Reproductive Research

Ongoing research indicates that P. hirsuta does not self-pollinate and relies on insects to vector pollen to set fruit and produce seed (Ferguson 2004). Seed set in a subsample of P. hirsuta plants ranged between 78 and 92 percent and seed viability was recorded as high as 84 percent (Ferguson 2004, Ferguson and Filipski 2005). Of viable seeds that were planted in pots in the laboratory, 68.5 percent produced viable seedlings. Seedlings raised in a greenhouse took 4 to 22 days to emerge from the soil (Ferguson and Filipski 2005).

  • 09/01/2020
  • Orthodox Seed Banking

Based on an September 2020 extract of the California Plant Rescue Database, California Botanic Garden holds 2 accessions of Phlox hirsuta in orthodox seed collection. There are as many as 795 seeds of this species in their collection - although some may have been used for curation testing or sent to back up.

Nature Serve Biotics
  • 05/02/2017

Endemic to serpentine soils in Siskiyou County, northern California. Only 4 populations are currently known, located in and near the town of Yreka. The type location near the town of Etna has never been relocated. A significant portion of 1 the occurrences is located on land subdivided for housing development. Other threats aside from development include ORVs, logging, grazing and road construction. No sites are currently protected. There are only about 1500 total plants known, but accurate pop counts are needed.

Holly Forbes
  • 01/01/2010

Habitat Destruction Fire Suppression Logging Highway Maintenance Competition with non-native plants Herbicide Application Domestic Animal Grazing

Holly Forbes
  • 01/01/2010

Five populations of 200 to 10,000 plants. (Recovery Plan)

Holly Forbes
  • 01/01/2010

Ongoing research indicates that P. hirsuta does not self-pollinate and relies on insects to vector pollen to set fruit and produce seed (Ferguson 2004). Seed set in a subsample of P. hirsuta plants ranged between 78 and 92 percent and seed viability was recorded as high as 84 percent (Ferguson 2004, Ferguson and Filipski 2005). Of viable seeds that were planted in pots in the laboratory, 68.5 percent produced viable seedlings. Seedlings raised in a greenhouse took 4 to 22 days to emerge from the soil (Ferguson and Filipski 2005).

Holly Forbes
  • 01/01/2010

In 2005 the City of Yreka erected earthen berms in three locations of the Greenhorn Creek occurrence to prevent further off-road vehicle and other types of recreational damage to Yreka phlox plants and habitat. In 2005, Siskiyou County staff mapped noxious weed locations and removed 127 Isatis tinctoria plants from China Hill to prevent them from going to seed. Control of I. tinctoria will require a dedicated and continuing effort. (Recovery Plan)

Holly Forbes
  • 01/01/2010

Demographic and ecological research needed. Seed dispersal in habitat Seed germination in habitat Seedling establishment in habitat Studies of life history, breeding system, pollinators, and effects of soil disturbance and fire management are needed.

Holly Forbes
  • 01/01/2010

Long term seed bank. Development of propagation techniques

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Photos
Nomenclature
Taxon Phlox hirsuta
Authority E. Nels.
Family Polemoniaceae
CPC Number 3394
ITIS 504318
USDA PHHI7
Common Names Yreka Phlox
Associated Scientific Names Phlox hirsuta | Phlox stansburyi var. hirsuta
Distribution Yreka phlox is currently known to occur on China Hill in Yreka; on the north and south sides of Greenhorn Creek, west of the Yreka city limits; on the western edge of Yreka near Jackson Street; and in
State Rank
State State Rank
California S1
Habitat

Yreka phlox is endemic to serpentine substrates (i.e., found only on soils derived from ultramafic parent rocks) from near 900 meters to 1,300 meters elevation. It grows on shallow to somewhat deep soils with moderate to high erosion potential. Vegetation ranges from serpentine barrens to openings in juniper, oak, or pine woodlands. (Recovery Plan)

Ecological Relationships

Field observations suggest that its populations may be stable, individual plants may be long-lived, and seedling establishment is infrequent. (Recovery Plan)

Pollinators
Common Name Name in Text Association Type Source InteractionID

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