CPC Plant Profile: Otay Mountain Ceanothus
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Plant Profile

Otay Mountain Ceanothus (Ceanothus otayensis)

Photo Credit: John Rusk
Description
  • Global Rank: G1 - Critically Imperiled
  • Legal Status: N/A
  • Family: Rhamnaceae
  • State: CA
  • Nature Serve ID: 129052
  • Date Inducted in National Collection: 09/18/2021

Ceanothus otayensis is known as the Otay Mountain lilac. This critically imperiled shrub is distinct in the genus, with a short growth habit and small, thick leaves, and is found almost exclusively on Otay Mountain and neighboring San Miguel Mountain.

Participating Institutions
Updates
  • 10/09/2020
  • Demographic Research

A 2014 study conducted by Dr. Dylan O. Burge, Ph.D. from California Academy of Sciences investigated the role of soil chemistry in the geographic distribution of Ceanothus otayensis. Sedimentary and metavolcanic soils of C. otayensis proved to be chemically indistinguishable from one another, which may help explain its disjunct distribution (Burge 2014).

  • 09/01/2020
  • Orthodox Seed Banking

Based on an September 2020 extract of the California Plant Rescue Database, Santa Barbara Botanic Garden holds 1 accessions of Ceanothus otayensis in orthodox seed collection. There are as many as 50 seeds of this species in their collection - although some may have been used for curation testing or sent to back up.

  • 09/01/2020
  • Orthodox Seed Banking

Based on an September 2020 extract of the California Plant Rescue Database, San Diego Zoo Global holds 2 accessions of Ceanothus otayensis in orthodox seed collection. There are as many as 46521 seeds of this species in their collection - although some may have been used for curation testing or sent to back up.

  • 08/05/2020
  • Seed Collection

Based on an August 2020 extract of the California Plant Rescue Database, San Diego Zoo Global has collected 2 seed accessions of Ceanothus otayensis from 2 plant occurrences listed in the California Natural Diversity Database. These collections together emcompass 261 maternal plants

  • 08/05/2020
  • Seed Collection

Based on an August 2020 extract of the California Plant Rescue Database, Santa Barbara Botanic Garden has collected 1 seed accessions of Ceanothus otayensis from 1 plant occurrences listed in the California Natural Diversity Database. These collections together emcompass 10 maternal plants

Joe Davitt
  • 08/22/2017

Interestingly, a very small population was discovered roughly 20 miles north of these populations. Soil studies have shown that this small population is growing in soil almost identical in mineral composition to soils found on Otay Mountain. It’s unclear if this population migrated to this location, taking advantage of the similar soil type, or if it is a remnant population, from a time when the species was more widespread.

Joe Davitt
  • 08/02/2017

The San Diego Zoo Global Native Plant Seed Bank made two collections from populations on Otay Mountain in 2016.

Ryan Fitch
  • 04/12/2017

The alteration of fire regimes and Border Patrol activities both serve as a serious threat to this species (CNPS 2017).

Ryan Fitch
  • 04/12/2017

In recent (<=20 years), there have been 20 populations of the species. There are currently 26 known extant occurrences within these populations (CNPS 2017).

Ryan Fitch
  • 04/12/2017

A 2014 study conducted by Dr. Dylan O. Burge, Ph.D. from California Academy of Sciences investigated the role of soil chemistry in the geographic distribution of Ceanothus otayensis. Sedimentary and metavolcanic soils of C. otayensis proved to be chemically indistinguishable from one another, which may help explain its disjunct distribution (Burge 2014).

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Photos
Nomenclature
Taxon Ceanothus otayensis
Authority
Family Rhamnaceae
CPC Number 44842
ITIS 28493
USDA CEOT
Common Names Otay Mountain buckbrush | Otay Mountain lilac | Otay ceanothus
Associated Scientific Names Ceanothus otayensis | Ceanothus × otayensis
Distribution As its species name implies, it is found almost exclusively on Otay Mountain, with small populations on neighboring San Miguel Mountain and at least one population known in northern Baja, just across the boarder from Otay Mountain.
State Rank
State State Rank
California S1
Habitat

This species can be found on rocky slopes, chaparral, dry slopes, and brushlands at elevations of 600-1100 m.

Ecological Relationships

Pollinators
Common Name Name in Text Association Type Source InteractionID

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