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Locally Rare Vascular Plants in the Santa Cruz Mtns

Oakmead Herbarium home

The concept of Local Rarity references uncommon plants other than the more publicized, better appreciated, and often better surveyed State-, Federal-, and CNPS-listed Special Status Plants. The California Environmental Quality Act (CEQA) allows consideration of Locally Rare species (Wood 2014). Through the lens of Local Rarity the significance of the JRBP vascular plant assemblage is even greater than that conveyed by total taxa and other commonly used measures of floristic richness.In view of documented Preserve species loss and declines and the typically small population size of the Locally Rare-designated plants, one is reminded of the importance of systematic restoration and invasive plant interventions to enhance the prospects of sustaining the Preserve's biodiversity.  A remarkable insight from preliminary work (based on extensive fieldwork and a draft inventory developed from Toni Corelli's 2011 Checklist of the Vascular Plants of San Mateo and Santa Clara Countiesalong withSan Francisco and Santa Cruz Co. data)is that perhaps 20% of the flora of the Santa Cruz Mountains2 -- on the order of 425 plants -- are Locally Rare with five or fewer locations, and approximately 20% of those plants are documented for JRBP. The separate watchlist of uncommon plants includes about 100 taxa of which half are documented for the Preserve; we expect some of these to be reclassified as the project develops and more information is available. Eighteen percent of the Preserve's native flora are Locally Rare or Special Status Plants (102 of 572 terminal aka minimum level taxa: species, subspecies, varieties).

Checklist of Jasper Ridge Biological Preserve Locally Rare Plants

Table 1. Special Status Plants (State-, Federal-, and CNPS-listed)
Table 2Locally Rare (draft, provisional working list)
Table 3Watchlist  (draft, provisional working list)

  • The provisional database for San Mateo Co. and the Santa Clara Co. portion of the Santa Cruz Mtns (developed from Toni Corelli's 2011 Checklist of the Vascular Plants of San Mateo and Santa Clara Counties) simply requires documentation of a taxon in 5 or fewer parks or preserves for Locally Rare status. Plants occurring in 6-9 locations are placed on a watchlist. Exceptions have been made. Data is for apr 100 properties/parks/preserves. Locally Rare status therefore indicates a plant is documented for no more than 5% of the properties. A  floristic region approach (subregions) to our counties may be developed in the future after the example of CNPS East Bay and Santa Cruz Co. chapters in their checklists.  Locally rare plants with only 1 or 2 locations number ~200 taxa. 
  • We also follow the Locality Data Convention of the CNPS Santa Cruz Co. of upper and lower case location names, UPPER CASE JRBP signifying documentation 1995 or more recent, lower case jrbp signifying only pre-1995 documentation. (Neubauer, 2013:11)
  • Obviously only current populations should be considered when designating a taxon locally rare. Across the bioregion data are frequently from cumulative checklists and historical records that do not answer the questions 1) is a taxon currently present on a specific preserve; and 2) is the taxon population stable, etc?  However, Jasper Ridge Biological Preserve data are supported by an active collecting program and 6000+ herbarium vouchers, thousands of  geo-referenced photo vouchers, and other documentation. Photos are archived in Flickr. Thomas (1961) is the single most complete source for what would now be considered historical records covering the entire region; his voucher-based location information has largely been aggregated by the Consortium of California Herbaria (CCH) and Calflora. Many of these old records/reports have sketchy location information.
  • There is a CNPS Santa Clara Valley Chapter resource page for listed plants of San Mateo and Santa Clara counties. 



1In addition to number of taxa, special status (listed) plants, vegetation types, plant associations, habitats and special soils, there are other ways of characterizing the Preserve's vascular flora and its significance to our bioregion, the Santa Cruz Mountains. Ecologists and taxonomists are currently analyzing local and regional floras state-wide in terms of evolutionary diversification, divergence, and survival by combining spatial information from herbarium collections and DNA-based phylogenies (Kling et al. 2018), others are using LIDAR and other enhanced vegetation mapping techniques. Lineages of Jasper Ridge plant families can be viewed on the chart Phylogenetic guide to Jasper Ridge Vascular Plant Families.

2 The Santa Cruz Mountains, a section of California's outer Coast Range, form a distinct geographical and biological unit. They are separated from the North Coast Ranges by the Golden Gate, from the Diablo Range to the east by San Francisco Bay and the Santa Clara Valley, from the Santa Lucia Mountains and Salinas Valley by the Pajaro River, and the Pacific Ocean forms the western boundary. (Thomas, 1961: p. 4-5) The Santa Cruz Mountains region is about 1386 square miles (887,040 acres, 358,972 hectares) includes all of San Mateo, Santa Cruz, and San Francisco counties, and the western portion of Santa Clara Co. [Some workers consider San Francisco south to San Bruno mountain a different, generally formerly treeless zone that has been termed Franciscan by James Roof]. The Santa Cruz Mountains hosts three CNPS chapters. The Jepson Flora Project geographical subdivisions that include our region of the California Floristic Province are SNFrB (San Francisco Bay Area) and CCO (Central Coast). 

Corelli, Toni. 2011. Checklist of the Vascular Plants of San Mateo and Santa Clara Counties, CA. CNPS.
Corelli, Toni. 2019. Locally Rare Taxa San Mateo County (Updated 9/6/2019). Unpublished.
Kling et al. 2018. Facets of phylodiversity: evolutionary diversification, divergence and survival as conservation targets. 2018.DOI: 10.1098/rstb.2017.0397.
Lake, D. 2021.  Improving the Way We Assess Rarity in the Unusual Plants Project. CNPS East Bay Chapter
Neubauer, D. 2013. Annotated Checklist of the Vascular Plants of Santa Cruz County, California. 2 ed. CNPS.
Thomas, John. 1961. Flora of the Santa Cruz Mountains of California: A Manual of the Vascular Plants. Stanford U.
Wood, M. 2014. CEQA and Locally Rare Plants.