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Creating new populations of Howell's spectacular thelypody
Working towards recovery
Howell's spectacular thelypody plants in greenhouse
outplanting Howell's spectacular thelypody
monitoring introduced Howell's spectacular thelypody population
Left: Howell's spectacular thelypody (Thelypodium howellii ssp. spectabilis) plants growing in the greenhouse. Middle: ODA staff outplanting thelypody rosettes to create a new population at a protected site in Baker County. Right: Monitoring an experimental population of Howell's spectacular thelypody that was created in 2002 at Baldock Slough - each flag represents one flowering individual. Photos by Rebecca Currin (left), Rhiannon Thomas (center), and Melissa Carr (right). If downloading images from this website, please credit the photographer.

Project Goals
To promote the recovery of Howell's spectacular thelypody (Thelypodium howellii ssp. spectabilis) by:

  • Investigating potential reproductive limitations facing this species
  • Providing basic biological and ecological information necessary for developing manangement, conservation, and recovery strategies
  • Developing seed germination and greenhouse cultivation protocols
  • Using these protocols to produce transplants for new population creation projects
  • Characterizing suitable habitat and developing habitat criteria to be applied when selecting outplanting sites
  • Locating appropriate thelypody habitat in permanently protected sites for the establishment of new populations
  • Establishing a series of new populations in those sites
  • Implementing a long term monitoring program for created populations

Project duration
1997 - present

Howell's spectacular thelypody is one of several rare Oregon species in the mustard family (Brassicaceae).  There are only 11 known locations of this species.  Ten of these populations occur on private land, and only two populations are currently administratively protected.  Primary threats to this species include loss and degradation of habitat due to agricultural usage, residential development, and grazing.  In response to these threats, ODA lists Thelypodium howellii ssp. spectabilis as Endangered, and U.S. Fish and Wildlife Service (USFWS) lists this species as Threatened. A Recovery Plan (pdf, 450 KB) specifying actions needed to recover this species, including creation of new populations, was issued by USFWS in 2002.

Research summary
  • Investigation of Howell's spectacular thelypody biology and ecology:  From 1997-1999, with the help of funding from U.S. Fish and Wildlife Service (USFWS), ODA staff conducted a series of greenhouse studies investigating the sex expression and reproductive capacity of Howell's spectacular thelypody.  Various morphological and phenological measurements were taken from randomly selected greenhouse-grown plants to learn more about the structural development of flowers.  Greenhouse-grown plants were also hand pollinated to evaluate the degree of self-compatibility in the species and determine the reproductive capacity of plants with access to non-limiting abiotic and pollen resources.  Pollinator surveys and detailed pollinator observations were conducted in the field at natural populations as well.
Thelypody flowers are hermaphroditic, bearing both male and female parts, and the plants are self-compatible.  However, this species is protandrous, with the release of pollen from the anthers commencing well before stigma receptivity.  There was no significant difference between the ratio of seeds to ovules/fruit for self-pollinated and cross-pollinated flowers.  In the field, Howell's spectacular thelypody attracts an abundance and wide variety of insect visitors, with bees being the most common.
  • Development of seed germination protocols: In 1997, ODA initiated a series of seed germination trials.  However, first year trials were unsuccessful.  In 1998 additional trials were initiated using seed collected in both 1997 and 1998.  While no 1997 seeds germinated in the 1998 trials, seeds collected in 1998 were more successful.  Optimal germination occurred after six weeks of cold stratification at 5˚ C, followed by removal from the cold.  Seeds did not germinate without cold stratification, nor did they germinate with only two weeks of cold stratification.
  • Development of off-site cultivation methods: Howell's spectacular thelypody proved to be relatively easy to cultivate off-site.  Newly germinated thelypody seedlings were planted in 4-inch plastic pots filled with pre-moistened potting medium consisting of peat moss and perlite, and placed under fluorescent and high-pressure sodium lamps.  Young plants were watered as needed, and liquid fertilizer was applied bi-weekly after seedlings developed true leaves. Plants placed outside in the greenhouse yard for three months of vernalization became dormant for the winter, but within 30 days of returning to the greenhouse they sprouted new leaves and started to bolt.  Plants kept within the greenhouse all winter did not bolt, but rather continued as non-reproductive rosettes.
  • Creation of new populations: In 2002, ODA worked with the Natural Resources Conservation Service (NRCS) to select administratively protected sites containing suitable habitat for the establishment of new populations of Howell's spectacular thelypody.  That year, a total of 520 seedlings were outplanted to create three experimental thelypody populations at Baldock Slough in Baker County.  In addition, 6,000 seeds were directly sown at each of the three sites.  In 2007, another four populations were created, with a total of 740 transplants and 29,500 directly-sown seeds installed at the four sites.  Annual monitoring of the newly established populations was conducted from 2002-2008.  As of June of 2008, all seven new populations persist, although some sites have been more successful than others.  Initial monitoring results indicate that both transplants and directly-sown seed can be used to establish new populations of Howell's spectacular thelypody.  However, selecting sites with suitable habitat and controlling non-native weed infestations are critical to the ongoing survival and expansion of the populations.

Future Work
ODA hopes to continue to monitor the created populations at Baldock Slough and cooperate with USFWS and NRCS to ensure the long term viability of these populations.  We also hope to identify new sites containing potential thelypody habitat to be used for future introduction efforts.   

Creating new populations of Thelypodium howellii ssp. spectabilis (Howell's spectacular thelypody): Baldock Slough introductions (pdf, 737 kB)
For more information about this species, visit the Howell's spectacular thelypody plant profile.