CPC Plant Profile: Tahoe Yellowcress
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Plant Profile

Tahoe Yellowcress (Rorippa subumbellata)

The coastal habitat where this species is found. Photo Credit: Gail Durham
Description
  • Global Rank: N/A
  • Legal Status: N/A
  • Family: Brassicaceae
  • State: CA, NV
  • Nature Serve ID: 153949
  • Date Inducted in National Collection: 04/04/1991

Lake Tahoe is a popular vacation destination for many Americans. Perhaps, too popular. This hot-spot for boaters and sunbathers is the only naturally occurring site of the Lake Tahoe yellowcress. Rorippa subumbellata inhabits a seven-foot "tidal" zone between the low and high water lines of Lake Tahoe. This low-growing perennial has proven to be adaptable from year to year depending on the amount of rainfall. During years with low rainfall, the cress can grow lower on the exposed beach from seed or rootstock. In years of higher rainfall, the cress is limited by the availability of exposed beach. This delicate lakefront habitat is threatened by constant abuse from boat wake, dock construction, and uncontrolled recreation. Due to continuous abuse of the unique Lake Tahoe yellowcress habitat, only an estimated 14 of the 48 historically known populations survive. Efforts are being made to limit construction and the degradation of the yellowcress' habitat. This mustard family member has been listed as "Endangered" by the state of California since 1982 and "Critically Endangered" by the state of Nevada since 1980. On December 11th 2000, the League to Save Lake Tahoe and the Center for Biological Diversity submitted a formal petition to the U.S. Fish & Wildlife Service to list the Tahoe yellow cress as an Endangered species. Without federal protection and the efforts of local conservationists and Tahoe area residents, the plant will continue to slide toward extinction.

Participating Institutions
Updates
  • 10/18/2020
  • Demographic Research

In 1999, the Tahoe-Baikal Institute directed a study to monitor all populations of the Tahoe Yellowcress. They designed a protocol that could be followed to monitor the plant from year to year. They also recommended future management strategies that may contribute to the conservation of the Tahoe yellowcress in the basin. A draft Conservation Strategy is being written and should be finalized and distributed in the spring of 2002 (Gross, pers. comm.) [Less...] Public Profile by Edward

  • 10/18/2020
  • Reintroduction

Sites managed by the US Forest Service and California State Parks are monitored regularly and are fenced to reduce or eliminate recreational disturbances (USFWS 2000). Three sites on U.S. Forest Service land were planted with 500 seedlings each in 1988. Populations were surveyed in 1990 and again in 1993. There was an overall survival rate of 12 to 43% (California State Lands Commission 1998). In 1999, the Tahoe-Baikal Institute directed a study to monitor all populations of the Tahoe Yellowcress. They designed a protocol that could be followed to monitor the plant from year to year. They also recommended future management strategies that may contribute to the conservation of the Tahoe yellowcress in the basin. A draft Conservation Strategy is being written and should be finalized and distributed in the spring of 2002 (Gross, pers. comm.)

  • 10/18/2020
  • Reproductive Research

Ongoing biological studies by the Tahoe-Baikal Institute. Student interns have studied human disturbances, monitored populations, and observed the pollinators of Rorippa subumbellata.

  • 10/18/2020
  • Propagation Research

Germination trials at The Berry Botanic Garden yielded no germination of apparently good seed. Seeds were either cold stratified or not, and then subjected to either constant 68F (20C) or alternating 50F/68F (10C/20C) temperatures. Further research is needed to determine optimum germination requirements (BBG File). If no success is achieved, seed viability tests should be conducted.

  • 10/18/2020
  • Genetic Research

Determination of genetic diversity through isozyme analysis. Samples from 11 populations around the lake were analyzed to determine the genetic diversity within and between sites. The results show extremely limited variation. Eight of the eleven populations were identical for the 23 loci examined (all homozygous). The remaining three populations were nearly identical. They were nearly homozygous except for one or two loci, which were variable. The results indicate very low levels of gene flow and suggest that most plants around the lake may be a single clone (NFGEL 2000)

  • 10/18/2020
  • Cryo

Seed germination was found to be stimulated by in vitro germination in the presence of cytokinin (Pence 2006). In vitro propagation and cryopreservation protocols were also developed for this species at CREW.

  • 10/18/2020
  • Propagation Research

Seed germination was found to be stimulated by in vitro germination in the presence of cytokinin (Pence 2006). In vitro propagation and cryopreservation protocols were also developed for this species at CREW.

  • 09/01/2020
  • Orthodox Seed Banking

Based on an September 2020 extract of the California Plant Rescue Database, California Botanic Garden holds 5 accessions of Rorippa subumbellata in orthodox seed collection. There are as many as 110740 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, Rae Selling Berry Seed Bank & Plant Conservation Program holds 3 accessions of Rorippa subumbellata in orthodox seed collection. There are as many as 2689 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, Rae Selling Berry Seed Bank & Plant Conservation Program has collected 3 seed accessions of Rorippa subumbellata from 3 plant occurrences listed in the California Natural Diversity Database. These collections together emcompass 3 maternal plants

Valerie Pence
  • 01/08/2018

Seed germination was found to be stimulated by in vitro germination in the presence of cytokinin (Pence 2006).  In vitro propagation and cryopreservation protocols were also developed for this species at CREW.

Nature Serve Biotics
  • 05/02/2017

Tahoe yellow-cress is known from approximately 44-63 occurrences. There are many historical occurrences. The species occupies a very narrow habitat band within the shore zone of Lake Tahoe, California and Nevada. The habitat experiences heavy recreational use at most sites, and is regularly subject to major contractions caused by maintenance of artificially high water levels in Lake Tahoe, with resulting further concentration of beach impacts in the habitat remaining exposed. Only the two largest occurrences (and about 20-35% of the total sub-EOs) remain active during prolonged periods of high water. Portions of the lakeside habitat have been developed for casinos (on the Nevada side of the lake) and for other tourism-related facilities, and many other portions are in heavily visited parklands.

Edward Guerrant, Ph.D.
  • 01/01/2010

Habitat destruction (beach houses, boat ramps, recreation, etc) (Reynolds 1988). Soil/sand disturbance (CA Dept. of Parks and Recreation 1991). Rising lake levels (Reynolds 1988). Grazing (Ferreira 1986).

Edward Guerrant, Ph.D.
  • 01/01/2010

There are approximately 42 different sites around the lake where Rorippa subumbellata has been found at some point since surveys began in 1979. Many may have been extirpated, and populations seem to come and go depending on the conditions (California State Lands Commission 1998). In 1999, 14 sites were observed: 5 on private property, 9 on federal land. The number and size of populations fluctuates with changing lake levels (USFWS 2000).

Edward Guerrant, Ph.D.
  • 01/01/2010

Determination of genetic diversity through isozyme analysis. Samples from 11 populations around the lake were analyzed to determine the genetic diversity within and between sites. The results show extremely limited variation. Eight of the eleven populations were identical for the 23 loci examined (all homozygous). The remaining three populations were nearly identical. They were nearly homozygous except for one or two loci, which were variable. The results indicate very low levels of gene flow and suggest that most plants around the lake may be a single clone (NFGEL 2000) Germination trials at The Berry Botanic Garden yielded no germination of apparently good seed. Seeds were either cold stratified or not, and then subjected to either constant 68F (20C) or alternating 50F/68F (10C/20C) temperatures. Further research is needed to determine optimum germination requirements (BBG File). If no success is achieved, seed viability tests should be conducted. Ongoing biological studies by the Tahoe-Baikal Institute. Student interns have studied human disturbances, monitored populations, and observed the pollinators of Rorippa subumbellata.

Edward Guerrant, Ph.D.
  • 01/01/2010

Sites managed by the US Forest Service and California State Parks are monitored regularly and are fenced to reduce or eliminate recreational disturbances (USFWS 2000). Three sites on U.S. Forest Service land were planted with 500 seedlings each in 1988. Populations were surveyed in 1990 and again in 1993. There was an overall survival rate of 12 to 43% (California State Lands Commission 1998). In 1999, the Tahoe-Baikal Institute directed a study to monitor all populations of the Tahoe Yellowcress. They designed a protocol that could be followed to monitor the plant from year to year. They also recommended future management strategies that may contribute to the conservation of the Tahoe yellowcress in the basin. A draft Conservation Strategy is being written and should be finalized and distributed in the spring of 2002 (Gross, pers. comm.) Seeds from three sites are stored at The Berry Botanic Garden.

Edward Guerrant, Ph.D.
  • 01/01/2010

Fence populations (Ferreira 1986). Investigate possible mycorrhizal associations and other vegetation relationships. Maintain and protect populations, especially the three largest, which contain different alleles than the smaller populations (NFGEL 2000). Determine how long dormant plants can survive inundation by lake water. Determine the dominant method of site colonization. Is it by seed, re-sprouting roots, or deposition of plant material (i.e. fragments) Determine success of reproduction. Study the longevity and viability of seeds. Study pollination and reproductive biology. Determine patterns of gene flow. If worse comes to worst, manipulate lake levels in order to create more suitable habitat and promote establishment. Study the biological and ecological reasons for this species' rarity, including: population structure and dynamics, life history, and environmental requirements (California State Lands Commission 1998).

Edward Guerrant, Ph.D.
  • 01/01/2010

Determine germination requirements. Determine if seeds can effectively be stored for long periods of time. Collect and store seeds from populations around the lake, especially from populations that contain unique genes. Determine effective propagation and re-introduction methods.

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Photos
Nomenclature
Taxon Rorippa subumbellata
Authority Rollins
Family Brassicaceae
CPC Number 3773
ITIS 23016
USDA ROSU2
Common Names marsh cress | Tahoe yellow-cress | Lake Tahoe yellowcress | Tahoe yellowcress
Associated Scientific Names Rorippa subumbellata
Distribution NV: Carson City, Douglas County, Washoe CountyCA: n SNH- northern High Sierra Nevada (Lake Tahoe Basin) (El Dorado and Placer Co.)Beaches surrounding Lake Tahoe
State Rank
State State Rank
California S1
Nevada S1
Habitat

Coarse sand and sandy soil of beaches, dunes, stream inlets, and backshore depressions along the shore of Lake Tahoe, high in the Sierra Nevada Mountains, almost exclusively between the elevations of 6223 ft and 6230 ft.

Ecological Relationships

Fluctuating water levels both help and hinder this species. This plant thrives in years when the water level is lower and there is less competition from plants that require moisture. (CA Dept. of Parks and Recreation 1991). The lower water level also creates more available habitat. In years with high lake levels, the habitat becomes unavailable for colonization and prolonged exposure water may kill individuals. However, occasional high water levels may benefit Tahoe yellowcress by removing other plant species eventually opening up new habitat. Before damming, water levels fluctuated on a yearly cycle. Levels were highest in the fall and winter and lower in the spring and summer. Now, because of stream damming, levels remain fairly constant. High water is maintained in the spring and summer months, which is the growing season of Rorippa subumbellata (NFGEL 2000). Seed and plant material may be dispersed by wind and wave action, leading to colonization of new sites (NFGEL 2000). Associated species include: Carex douglasii, Phacelia hastata var hastata, Juncus balticus, Salix spp., Lepidium virginicum var. pubescens, various grasses. (Reynolds 1988). Little is known about the reproductive biology of this species. The method of pollination is not known (NFGEL 2000).

Pollinators
Common Name Name in Text Association Type Source InteractionID
Bees
Leaf-cutting bees Megachilidae Suspected Pollinator Floral Link
Mining bees Andrenidae Suspected Pollinator Floral Link
Flies
Longlegged flies Dolichopodidae Floral Visitor Link
Syrphid flies Syrphid flies Floral Visitor Link
House flies and kin Muscidae Floral Visitor Link
Other
Tiphiid wasps Tiphiidae Suspected Pollinator Floral Link

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