Physaria x 1

Brassicaceae (Mustard Family)

Close up of Physaria vitulifera x bellii by Teresa Burkert.
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Close up of Physaria vitulifera x bellii by Teresa Burkert.
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Close up of Physaria vitulifera x bellii in fruit by Pamela Smith.
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Close up of Physaria vitulifera x bellii by Pamela Smith.
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Taxonomic Comments

This record is for the entity Physaria vitulifera x P. bellii.

Ranks and Status

Global rank: GNA
State rank: S1
Federal protection status: None
State protection status: None

[+] Description and Phenology

Physaria vitulifera x bellii by Teresa Burkhert.
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General description: Physaria x1 is a hybrid species resulting from a cross between Physaria vitulifera and P. bellii.  A hybrid had been suggested by botanists visiting populations of plants that appeared to have intermediate morphological characteristics of the two species.  Genetic investigations conducted on these populations with intermediate characters confirmed the existence of a hybrid as an entity distinct from either of the two parents (Kothera 2007). This study also included an analysis of leaf morphology data which demonstrated the hybrids were different from the parental species and that the leaf characters were intermediate between the two. The leaves of Physaria x 1 are often fiddle-shaped with incised margins. The fruits are irregular and wrinkly. The sinus at the top and bottom of the fruit appear subequal.

Look Alikes: This hybrid could be confused with Physaria bellii, or Physaria vitulifera. Physaria vitulifera has larger, fiddle shaped leaves, and the constriction separating the locules of the fruit is much deeper above than below. The basal leaf margins on P. bellii are not incised, while they are deeply and broadly incised on P. vitulifera. The hybrid species, P. vitulifera x bellii has incised leaves, though less than in P. vitulifera, and wrinkly fruits (Ackerfield 2012, Smith et al. 2011).

Phenology: Flowers April-May, fruit in June-July.

[+] Habitat

Habitat of Physaria vitulifera x bellii by Pamela Smith.
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This hybrid plant species is found on hogback ridges composed of sedimentary rocks (shale, red sandstone and limestone soils). Sites are dry, south and west facing, and steep. Dominant plant communites are foothills shrublands.  Associated species include: Krascheninnikovia lanata, Oryzopsis hymenoidesComandra umbellata, Cercocarpus montanus, Rhus aromatica subsp. trilobata, Pascopyrum smithii, Penstemon secundiflorus, Yucca glauca, Hesperostipa comata. Nassella viridula, Mahonia repens, Stanleya pinnata, Helianthus pumila, Oenothera howardii, Quercus gambelii, Psoralidium tenuiflorum, and Lomatium orientale (Colorado Natural Heritage Program occurrence records as of 2017).

Elevation Range: 5,627 - 6,253 feet (1,715 - 1,906 meters)

[+] Distribution

Distribution of Physaria vitulifera x bellii in Colorado according to mapped land ownership/management boundaries (CNHP 2017, COMaP).
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Distribution of Physaria vitulifera x bellii in Colorado.
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Colorado endemic: Yes
Global range: Colorado endemic, known only from Jefferson County.

[+] Threats and Management Issues

Known occurrences are found in natural areas and open spaces. Threats include game and social trails running through the occurrences, and competition from and/or unintended consequences of controling numerous non-native plants. Avoiding development of trails or other construction activities would likely ensure that these populations can continue to exist in this area. Colorado climate scenarios for 2050 suggest temperature will increase by 3-7 F and precipitation may decrease or increase. The impact to any given rare plant habitat is likely to vary. Long-term monitoring that includes weather and soil moisture data is critical to understanding climate impacts.

[+] References

    • Colorado Natural Heritage Program and the Geospatial Centroid. 2017. The Colorado Ownership and Protection Map (COMaP). Colorado State University, Ft. Collins, CO.
    • Kothera, L., S. M. Ward, and S. E. Carney. 2007. Assessing the threat from hybridization to the rare endemic Physaria bellii Mulligan (Brassicaceae). Biological Conservation 140: 110-118.
    • NatureServe. Unpublished. Concept reference for taxa which have not yet been described; to be used as a placeholder until a citation is available which describes the circumscription of the taxon.

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