|Bradshaw's desert-parsley, Bradshaw's lomatium, Bradshaw's parsley|
|(Rose ex Mathias) Mathias & Constance|
|Edward Guerrant, Ph.D.|
The following Participating Institutions are custodians for this species in the CPC National Collection:
Rae Selling Berry Seed Bank & Plant Conservation Programs
The conservation of Lomatium bradshawii is fully sponsored.
Edward Guerrant, Ph.D. contributed to this Plant Profile.
Lomatium bradshawii was once common, inhabiting the extensive native prairies of the Willamette Valley, creating carpets of sulfur-yellow in the spring. Like many other prairie species, Bradshaw's lomatium has been adversely affected by the extensive conversion of its habitat to agricultural and other uses by humans. Today, less than 1% of the Willamette Valley remains undisturbed. Lomatium bradshawii was believed to be extinct until a graduate student at the University of Oregon re-discovered it while jogging. Since its rediscovery in 1979, extensive research has been done to understand the ecology of this species. A majority of the remaining populations in Oregon are within a 10-mile (16 km) radius of the city of Eugene. Continued growth of the city threatens the future of these sites. In Washington, two recently discovered sites contain as many plants as are found in all of Oregon. However, both sites are on private land and are not subject to legal protection.
Distribution & Occurrence
Moist meadows and remnant prairie patches at low elevations. Associated species include Deschampsia cespitosa, Hordeum brachyantherum, Poa pratensis, Perideridia spp., Juncus spp., Grindelia integrifolia, Microseris laciniata, and Galium cymosum.
OR: Central and Southern Willamette Valley (Benton, Lane, Linn, and Marion Counties)
WA: Puget Trough, Southwestern Washington, Clark County
|As of 1992: 38 element occurrences (Oregon Natural Heritage Database) in three population centers. Populations are generally small, from fewer than 10 to about 1000 individuals. One large site contains 30,000 individuals.
In Washington, two populations were discovered in 1994. Both are on private land. One site has "several thousand" and another has approximately 70,400 individuals (WA Natural Heritage Database).
Conservation, Ecology & Research
Flowers may be either male (stamens only) or hermaphroditic (male/female-stamens and pistil). On hermaphroditic flowers, the stigmas become receptive to pollen before the anthers shed their pollen. The first umbel on a plant will often have a majority of male flowers. By having the male and female parts of each plant temporally isolated (difference in timing of flowering), the potential for self-pollination is reduced (Kaye, 1992).
A wide variety of bees, flies, wasps and beetles visit the flowers of Lomatium bradshawii and are likely pollinators (Kaye, 1992).
Cattle have been shown to have both negative and positive effects on Lomatium bradshawii. Cattle eat and trample the plants and disturb the soil. Fencing has been used to effectively exclude cattle. Despite these negative impacts, carefully controlled and monitored grazing may help in maintaining the habitat of L. bradshawii, by preventing woody plant encroachment. Before European-American settlement, both natural grass fires and fires set by Native Americans served to restrict the growth of woody vegetation and keep the grasslands open. Now, cattle may provide a similar service if used carefully.
Pesticides that kill the pollinators necessary for this plant to reproduce (Kaye and Kirkland, 1994).
Non-native plant invasion (Drew 2000).
Invasion of shrubs due to fire suppression (Kay
Field experiments and observations to determine breeding system and pollinators. Pollinator exclusion experiments determined that although the species is self compatible, insect pollinators are required for seed production due to temporal separation of the male and female flower parts (Kaye and Kirkland, 1994).
Genetic analysis of Lomatium bradshawii using AFLP markers found high levels of genetic diversity. Because of large population sizes and high genetic diversity within most populations, inbreeding depression is not considered a threat to this species. Exceptions do exist. One Oregon population has fewer than 100 individuals and lower genetic diversity than nearby populations. One Washington population has low levels of genetic diversity despite its large size. If population sizes are maintained at or near current levels, the long-term genetic stability of the species appears good (Gitzendanner, 1998).
Evaluation of the effect of prescribed burning of Lomatium. bradshawii habitat. Over a period of 9 years, plots were burned 2-3 times in the fall. Crown area, plant height, number of flowers and number of fruit was determined. The initial response was positive in many plots, but overall, the results were inconsistent (Pendergrass et al, 1999).
Comparison of direct seeding and transplanting as methods of establishing plants for reintroduction- direct seeding was an effective method of establishing plants. When cover vegetation was first removed, seedling recruitment increased from 17% to 38%. Different soil amendments had no effect on seedling establishment. Data is still being collected on the effectiveness of transplantation (Kaye, Kuykendall, and Nelson, 2000).
Determination of optimum germination procedures. Pre-chilling for 0, 2, 4, 6, and 8 weeks was tested as well as germination at alternating temperatures 59F/77F or 68F/86F (15C/25C or 20C/30C respectively). Eight weeks of cold stratification resulted in the highest germination. Germination was also greater under the 59F/77F (15C/25C) temperature regime than 68F/86F (20C/30C). Further work is needed to determine if germination percentages can be increased by longer cold stratification times or different temperature regimes (Kaye and Kuykendall, 2000).
Germination trials at the Berry Botanic Garden resulted in a maximum germination of 100%. One and 13 year old seeds subjected to 8 weeks of cold stratification followed by alternating 50/68F (10/20C) both germinated at a rate of 80%, while a constant 68 F (20C) resulted in 70% and 50% respectively. After 16 weeks cold stratification, one and 13 year old accessions yielded 70% and 90% germination respectively when subjected to the alternating temperature treatment, and 100% and 90% respectively at the constant temperature (BBG File).
Study of the effects of livestock grazing and small mammal depredation on Lomatium bradshawii. Late-season livestock grazing (after fruit maturation) lead to an increase in emergence of new plants and in the density of plants with multiple umbels, but did not alter survival or population structure. This may be due to small disturbances of the soil and a reduction in shading by nearby plants. Small mammal depredation was lowest in plots that were subjected to grazing. Presumably, livestock grazing reduces standing crop biomass (residual cover), thereby changing the habitat for small mammals. The long-term effects are not known (Drew, 2000).
Three occurrences in Oregon are on land designated as a "Wetlands Special Study Area."
A salvage operation was undertaken in 1999 at a development site in southern Washington. Road construction and development of a golf course was planned for the area in which the plants grew. Since the land was private, no regulations prohibited the owner from paving over the plants. Berry Botanic Garden employees and volunteers removed plants from the area where the road was to be built and brought them to the BBG to become part of the living collection.
The recovery plan was finalized in 1993. In 1994, two additional populations were discovered in Washington. An amendment to the recovery plan added the Washington populations as another recovery area. Lomatium. bradshawii can be downlisted to "threatened" when 10 populations are protected and managed to ensure their continued existence (US Fish and Wildlife Service).
Conservation Agreements for the two Washington populations were finalized in 1995 and 1998 (US Fish and Wildlife Service).
Manual control of woody plants and other invasive species has occurred at one of the Washington sites since 1997 (US Fish and Wildlife Service).
Both Washington sites have been monitored since 1997 (US Fish and Wildlife Service).
Seeds from Washington and Oregon populations stored at The Berry Botanic Garden. All recent collections (since 1998) are from one of the sites in Washington. Many seeds have been collected from garden grown plants. The last collection from wild populations in Oregon was in 1993.
Protect nesting habitat of native pollinators (Kaye and Kirkland, 1994).
Continue monitoring plots to determine long-term impact of different grazing intensities. Collect baseline data, map individuals, conduct demographic study (plant fates, etc) (Drew, 2000).
If warranted, utilize periodic late-season livestock grazing to maintain suitable habitat for Lomatium bradshawii. Determine the best time of year for grazing. Winter or early spring may be more beneficial than late-season grazing because L. bradshawii plants have not yet emerged (Drew, 2000).
Determine most appropriate intensity and periodicity of grazing (ex, light grazing every other year, moderate grazing every three years, heavy grazing every five years) (Drew, 2000).
Compare tree and brush removal, prescribed fire and mowing with livestock grazing in their effectiveness in maintaining Lomatium bradshawii (Drew, 2000).
Occasional burning of prairie habitat. Unfortunately, it is difficult to obtain permits for burning due to concerns of air pollution.
Determine reliable propagation and reintroduction protocols.