Date of Award


Degree Name

MS in Biological Sciences


Biological Sciences


College of Science and Mathematics


Matt Ritter

Advisor Department

Biological Sciences

Advisor College

College of Science and Mathematics


Globally we are experiencing a biodiversity crisis and potentially a sixth mass extinction event. Plant specimens are one of the best, most concrete records of biodiversity that we can create. Despite this, the rate of plant collecting has declined steeply since World War II. Now more than ever, plant collections are vital, both for the purpose of quantifying the plant biodiversity in an area and for discovering previously unrecognized diversity.

In Chapter 1, we conducted a floristic survey of the Cal Poly Swanton Pacific Ranch. The Swanton Pacific Ranch (SPR) is located north of the small town of Davenport California, in Santa Cruz county. SPR is 3,200 acres and contains areas of salt marsh, coastal bluff, coastal prairie, riparian forest, redwood forest, mixed conifer forest and chaparral in approximate ascending order of elevation. The property extends over an elevational gradient from 0 m to 420 m (1400 ft). We documented 634 taxa at SPR. In total, 974 specimens were collected during this project, 405 specimens in 2017 and 569 in 2019. We reviewed 211 historic specimens. We vouchered 546 taxa between 2017 and 2019 and observed but did not collect 6 taxa. 53 taxa are represented from historic collections and were not relocated. There are 30 taxa listed as historically present from personal observations of the authors but without vouchers. Though these do not have the same value as a physical specimen, we believe that all information is valuable and have included them with a clear indication of the source of the record. There were 465 native and 169 non-native taxa documented in the study area. There were 93 families represented, with Asteraceae, Poaceae and Fabaceae be ing the top three most speciose respectively. There were 83 taxa noted as locally rare following Neubauer, of these 16 taxa have a California Native Plant Society (CNPS) rare plant rank. We vouchered one new taxon for Santa Cruz County, Senecio aphanactis, which has a CNPS rare plant rank of 2B.2

In Chapter 2, we describe a new combination in the Sanicula crassicaulis species complex. During the project detailed in Chapter 1, we observed and collected several specimens that keyed to Sanicula crassicaulis Poepp. ex. D.C. but were notably distinct from other S. crassicaulis that we collected in the area. On further investigation, we found that these plants match the type specimen of S. nudicaulis Hook & Arn., described in 1839 and later synonymized with S. crassicaulis. This taxon is distinguished primarily by its long, sinuate marginal leaf trichomes, in contrast to the short, straight marginal trichomes of S. crassicaulis. Additionally, the length of the most proximal prickles on the schizocarps is about the same as the length of the most distal rather than the distal prickles being much longer as in S. crassicaulis and the angle of attachment of the prickles is more or less perpendicular as opposed to acute in S. crassicaulis. The known range of this taxon is between the San Francisco Bay Area and Santa Barbara County, generally near the coast. Here we recognize this taxon as a variety in S. crassicaulis, Sanicula crassicaulis var. nudicaulis. We provide a diagnosis, a map of the known range of the taxon and a key to the varieties of S. crassicaulis.

Overall this project has significantly increased or knowledge and documentation of the flora of both SPR and Santa Cruz county. In addition to the immediate benefits of this study (a complete species list for SPR, the discovery of a new taxon, and the mapping of all rare species at SPR) we have also contributed almost 1,000 physical specimens to the Cal Poly Hoover herbarium which may be used in future taxonomic and ecological studies.

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Biodiversity Commons