CPC Plant Profile: Peacock Larkspur
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Plant Profile

Peacock Larkspur (Delphinium pavonaceum)

Delphinium pavonaceum flowering stalk. Photo Credit: Vern Halloway
Description
  • Global Rank: G1 - Critically Imperiled
  • Legal Status: N/A
  • Family: Ranunculaceae
  • State: OR
  • Nature Serve ID: 146865
  • Date Inducted in National Collection: 03/05/1993

Between 13,000 and 15,000 years ago, a series of huge ice dams formed in Montana, backing up very large lakes. The dams occasionally broke unleashing immense amounts of water that tore through Oregon and Washington at tremendous speeds (nearing 90 miles per hour (144 kph)). The resulting Missoula floods caused intense destruction, altered stream courses, and destroyed established existing vegetation, but also brought in fresh deposits of silt and gravel. Scientists think that the Peacock larkspur (Delphinium pavonaceum), probably arose during this time, from either a mutation or from hybridization, and became established in sites disturbed by this flood. The peacock larkspur is found only in the Willamette Valley of Oregon. Presently, the natural vegetation of the Willamette Valley is experiencing a threat not altogether different in magnitude from the Missoula Floods - human development. Since nearly all grassland habitat has been converted to agricultural and residential use, the peacock larkspur is now found almost exclusively along fencerows and ditches where small patches of habitat have escaped complete destruction. But even the few populations that have escaped development are at risk. The white-flowered peacock larkspur appears to hybridize with a purple-flowered species and it is in danger of diluting the peacock larkspur's genetics until it is no longer is a distinct species (Goodrich 1983).

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Updates
  • 09/08/2020
  • Orthodox Seed Banking

Seeds from 5 sites stored at The Berry Botanic Garden.

  • 09/08/2020
  • Seed Collection

Seeds from 5 sites stored at The Berry Botanic Garden.

  • 09/08/2020
  • Reproductive Research

Comprehensive study of systematics, morphology, distribution, ecology, and reproductive dynamics (Goodrich 1983). A 1994 field survey found that populations varied in size from 3 to more than 2000 flowering individuals. Roadside plants appeared to be immanently threatened by the invasion of reed canary grass (Phalaris arundinacea) and other roadside weeds. Other sites appeared to be threatened by encroaching canopy of trees and tall shrubs (Finley and Ingersoll 1994) Observations indicated no evidence of hybridization with blue-flowered Delphinium menziesii where the two flowers co-occurred (Finley and Ingersoll 1994). Comparison between plants found in burned and unburned areas of a Research Natural Area (RNA) found that abundance, growth and reproduction was higher in burned areas. These observations are consistent with the hypothesis that frequent burning enhances growth and reproduction, but researchers note other factors that could contribute to the difference including a moisture gradient between the two areas (Finley and Ingersoll 1994).

  • 09/08/2020
  • Propagation Research

Germination trials at The Berry Botanic Garden indicate that a long period of cold stratification is required for germination. No seeds germinated when subjected to 8 weeks of cold stratification. When seeds were subjected to 12 weeks of cold stratification followed by constant 68F (20C) temperatures, 33% of the seeds germinated. With 12 weeks of cold stratification followed by alternating 50/68F (10/20C) temperatures, 14% of the seeds germinated (BBG file)

  • 09/08/2020
  • Genetic Research

Turner (1992) described the mitotic and meiotic chromosomes of four Oregon Delphinium species: D. trolliifolium, D. menziesii, D. pavonaceum and D. leucophaeum, for taxonomic comparison. Initial examination of chloroplast genetic variation within a population of Delphinium pavonaceum known to have color and chloroplast variation did not reveal the source of color variation or give insight to any past hybridization event (Mazer 2000).

Nature Serve Biotics
  • 05/02/2017

Edward Guerrant, Ph.D.
  • 01/01/2010

Urban expansion (Meinke 1982) Agricultural development (Meinke 1982) Herbicides (both agricultural and roadside) (Meinke 1982) Woody plant encroachment (Finley and Ingersoll 1994) Hybridization with a purple-flowered Delphinium (Karoly personal c

Edward Guerrant, Ph.D.
  • 01/01/2010

Historically, 35 occurrences known in Benton, Polk, Marion, Multnomah, and Clackamas counties. Only 18 occurrences have been seen since 1980. Population sizes range from as little as 1 to as many as 2000. Most have between 10 and 100 (ONHDB 2000).

Edward Guerrant, Ph.D.
  • 01/01/2010

Comprehensive study of systematics, morphology, distribution, ecology, and reproductive dynamics (Goodrich 1983). A 1994 field survey found that populations varied in size from 3 to more than 2000 flowering individuals. Roadside plants appeared to be immanently threatened by the invasion of reed canary grass (Phalaris arundinacea) and other roadside weeds. Other sites appeared to be threatened by encroaching canopy of trees and tall shrubs (Finley and Ingersoll 1994) Observations indicated no evidence of hybridization with blue-flowered Delphinium menziesii where the two flowers co-occurred (Finley and Ingersoll 1994). Comparison between plants found in burned and unburned areas of a Research Natural Area (RNA) found that abundance, growth and reproduction was higher in burned areas. These observations are consistent with the hypothesis that frequent burning enhances growth and reproduction, but researchers note other factors that could contribute to the difference including a moisture gradient between the two areas (Finley and Ingersoll 1994). Turner (1992) described the mitotic and meiotic chromosomes of four Oregon Delphinium species: D. trolliifolium, D. menziesii, D. pavonaceum and D. leucophaeum, for taxonomic comparison. Initial examination of chloroplast genetic variation within a population of Delphinium pavonaceum known to have color and chloroplast variation did not reveal the source of color variation or give insight to any past hybridization event (Mazer 2000). Germination trials at The Berry Botanic Garden indicate that a long period of cold stratification is required for germination. No seeds germinated when subjected to 8 weeks of cold stratification. When seeds were subjected to 12 weeks of cold stratification followed by constant 68F (20C) temperatures, 33% of the seeds germinated. With 12 weeks of cold stratification followed by alternating 50/68F (10/20C) temperatures, 14% of the seeds germinated (BBG file)

Edward Guerrant, Ph.D.
  • 01/01/2010

Seeds from 5 sites stored at The Berry Botanic Garden.

Edward Guerrant, Ph.D.
  • 01/01/2010

Maintain habitat in an undisturbed state (Meinke 1982). Mowing, hand removal of shrubs and trees, and prescribed burning to prevent encroaching shrubs and weedy species. Concurrent monitoring in order to assess the effectiveness of such techniques (Finley and Ingersoll 1994). Evaluate methods of controlling Phalaris arundinacea (reed canary grass) and implement effective measures (Finley and Ingersoll 1994).

Edward Guerrant, Ph.D.
  • 01/01/2010

Collect and store seeds from known populations. Determine optimum germination requirements. Determine propagation and reintroduction protocols.

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Photos
Nomenclature
Taxon Delphinium pavonaceum
Authority Ewan
Family Ranunculaceae
CPC Number 1387
ITIS 821198
USDA DEPA4
Common Names peacock larkspur
Associated Scientific Names Delphinium pavonaceum | Delphinium X pavonaceum
Distribution The Willamette Valley of Oregon.
State Rank
State State Rank
Oregon SNA
Habitat

Well drained areas of native prairie, especially roadsides that have escaped development (Meinke 1982). In floodplains, can be found on high mound areas that are better drained than surrounding prairie (Finley and Ingersoll 1994). Associated species include Potentilla gracilis, Deschampsia cespitosa, Poa pratensis, and Rosa spp. (Meinke 1982) and Spiraea douglasii (Finley and Ingersoll 1994). Along roadsides with Rubus spp., Rhus diversiloba, and Fraxinus latifolia (Finley and Ingersoll 1994).

Ecological Relationships

Delphinium pavonaceum is pollinated by bumblebees. In general, bumblebees prefer blue flowers or plants that reflect light in the UV range. It is possible that the white flowers of D. pavonaceum do reflect UV light to attract bumblebees. D. pavonaceum is self-compatible but apparently does not self-pollinate. It needs the insect vector to facilitate pollination. Observations indicate that plants may not flower until after their 5th year. It is difficult to determine how long an individual plant may live, but observations of plants with over 100 flowers indicate that they must have a relatively long life span. Larger plants may emerge and flower one year and be completely absent the next. Like many other larkspurs, D. pavonaceum exhibits this dormancy in response to available moisture (Goodrich 1983)Three threatened larkspurs: Delphinium oreganum, D. leucophaeum, and D. pavonaceum, are all restricted in their distribution to Oregon's Willamette Valley. Delphinium oreganum is intermediate in its floral and inflorescence traits, between the more common blue-flowered D. nuttallii and D. menziesii found in Oregon. Delphinium leucophaeum almost exactly resembles D. nuttallii in form, but its sepals are white instead of blue. D. pavonaceum is similar to D. menziesii in all features except flower color - it has white sepals and blue upper petals instead of blue sepals and white upper petals like D. menziesii. This concentration of rare plants from a single genus in such a limited geographical area raises interesting ecological and evolutionary questions. (Chambers 2000).Chambers (2000) hypothesizes that catastrophic flooding in the Willamette Valley during the Ice Age, between 15,000 and 12,800 years ago, was a catalyst for the evolution of these three rare species. At least 40 times, in roughly 50 year intervals, huge glacier-dammed lakes in Montana formed and broke, inundating over 16,000 square miles in Washington and Oregon. The Willamette Valley was flood-scoured at its north end and filled by a huge temporary lake. Repeated filling and draining of lake created large areas of habitat disturbance. New genetic forms of Delphinium, produced by either hybridization and/or mutation, may have established in these disturbed sites and evolved into the three present day endemic species. Notably, the present ranges of these endemics are limited to the area historically affected by these deluges.Delphinium oreganum appears to have arisen through genetic stabilization of hybridization between D. nuttallii and D. menziesii. In contrast, Delphinium leucophaeum and D. pavonaceum seem to have evolved directly from their respective parental taxa. Isolation through altered pollination behavior by insects, due to the changed flower-color pattern, seems a likely hypothesis in both cases (Chambers 2000). Goodrich (1983) discovered plants that she suspected of being of hybrid origin. These delphiniums have dark purple sepals rather than white ones characteristic of Delphinium pavonaceum. The upper petals are also dark purple, and the plants are morphologically similar to D. pavonaceum. The purple delphinium is only growing among white D. pavonaceum flowers (Karoly personal communication). The presence of what may be an undescribed species growing sympatrically with D. pavonaceum raises concerns about hybridization and the exchange of genetic material between them. Presently, the full impact of hybridization and gene exchange on native plant species is poorly understood. It is possible that genetic material from hybrids may undermine the genetic health and stability of the remaining Delphinium pavonaceum populations (Letter from Karoly to Northway).Turner (1992) examined chromosomes of four Oregon native Delphinium species in order to determine phylogenetic relationships. She found little differentiation between all four species in either the number or morphology of the chromosomes, indicating that there has been little chromosome evolution or it has been parallel in nature. Additionally, chromosome measurements indicated that the purple delphinium of suspected hybrid origin is most closely related to another Oregon species, D. trolliifolium. It can be surmised that D. trolliifolium is likely one of the parent species. Absence of structural heterozygosity in meiotic chromosomes suggests either no introgression (gene exchange), or that the chromosomes of the species are structurally, if not genetically similar. Absence of structural heterozygosity in purple delphiniums suggests that the karyotypes of parent species are similar. Alternatively, recurrent backcrossing may be diluting the hybrid genome. Lastly, the purple hybrid may not be a hybrid. Consistently high levels of seed production and germination among the purple delphinium reveals successful meiosis.Current genetic investigation is comparing chloroplast DNA with nuclear DNA (Mazer 2000). Since chloroplasts are inherited through the female (i.e.. mother) plant, genetic variation can be used to identify the extent of hybridization and the degree of introgression (Letter from Karoly to Northway). In order for genetic markers to be informative, researchers should compare populations of pure color forms. Observation and genetic analysis of one population indicates that it is a pure Delphinium. pavonaceum population, and therefore extremely valuable in determining the impact of hybridization on D. pavonaceum.

Pollinators
Common Name Name in Text Association Type Source InteractionID
Bees
Bumble bees Bumblebees Confirmed Pollinator Link
Reintroduction
Lead Institution State Reintroduction Type Year of First Outplanting

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