CPC Plant Profile: Leiberg's Clover
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Plant Profile

Leiberg's Clover (Trifolium leibergii)

Trifolium leibergii plants grow in a straight line because their roots extend down into cracks in the underlying rock. Photo Credit: Ed Florance
Description
  • Global Rank: G3 - Vulnerable
  • Legal Status: N/A
  • Family: Fabaceae
  • State: NV, OR
  • Nature Serve ID: 139752
  • Date Inducted in National Collection: 03/05/1993

In Oregon, Trifolium leibergii is restricted to an area that ranges 2 miles on either side of the Middle Fork of the Malheur River and continues for approximately 10 miles. Here, it grows on a distinct habitat characterized by a thin, gravelly soil layer consisting of decomposing (broken-down) volcanic ash "tuff." Underneath the thin layer of soil is the solid "tuff," which has deep cracks running through it. The taproot of Trifolium leibergii grows down into the cracks, causing neighboring plants to grow in a straight line (Nora Taylor, pers. comm.). This attractive clover is easily recognized by its three hairy "oak-leaf" shaped leaflets. When the plant first emerges in early spring, the leaves are a beautiful, succulent green. As the plant ages, the leaves fade to gray (and sometimes purple!). The small flowers are clustered into large heads, which start a creamy white and fade to a pretty pink as they age. The plant produces tiny pods with one or two seeds each (Nora Taylor, pers. comm.).

Participating Institutions
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Updates
  • 10/01/2020
  • Propagation Research

Germination trials at The Berry Botanic Garden. Seeds were either cold stratified for 8 weeks or not cold stratified. They were then placed in either constant 68F (20C) or alternating 50/68F (10/20C) temperature chambers. All treatments resulted in 100% germination (BBG File).

  • 10/01/2020
  • Propagation Research

Germination trials at Lewis and Clark College. Seeds germinated readily in both 41F (5C) conditions and 68F (20C) conditions (Florance 1994).

  • 10/01/2020
  • Orthodox Seed Banking

Seeds from 5 sites stored at The Berry Botanic Garden (BBG File).

  • 10/01/2020
  • Seed Collection

Seeds from 5 sites stored at The Berry Botanic Garden (BBG File).

Nature Serve Biotics
  • 05/02/2017

Known from about 23 sites in southcentral and southeastern Oregon (Harney and Malheur?County) and in northeastern Nevada (Elko County). Surveys in the 300 km-area between the presently known sites could turn up more populations. There are many large populations, with over 10,000 plants, in Nevada. Threats of trampling and grazing by cattle are minimal.

Edward Guerrant, Ph.D.
  • 01/01/2010

ORV use (Nora Taylor, pers. comm.) Cattle trails through habitat (Nora Taylor, pers. comm.) Possible threats to native pollinators.

Edward Guerrant, Ph.D.
  • 01/01/2010

As of 2001: 26 sites in Oregon with a total of approximately 38,000 individuals. Most sites are on Federal (BLM) or State (Oregon Department of Fish and Wildlife) owned land. Approximately 10% of individuals are on private land. Surveys have not been exhaustive, so it is possible that more populations exist (Nora Taylor, pers. comm.) 7 occurrences in Nevada with a total of approximately 136,000 individuals (NNHP 2001).

Edward Guerrant, Ph.D.
  • 01/01/2010

Germination trials at Lewis and Clark College. Seeds germinated readily in both 41F (5C) conditions and 68F (20C) conditions (Florance 1994). Germination trials at The Berry Botanic Garden. Seeds were either cold stratified for 8 weeks or not cold stratified. They were then placed in either constant 68F (20C) or alternating 50/68F (10/20C) temperature chambers. All treatments resulted in 100% germination (BBG File).

Edward Guerrant, Ph.D.
  • 01/01/2010

Recent searches in Oregon have revealed numerous new occurrences (Nora Taylor, pers. comm.). No monitoring on BLM land in Oregon as of 2001. A plan is being developed to begin monitoring populations in 2002 or 2003 (Nora Taylor, pers. comm.). Sites on BLM land in Oregon are on grazing allotments, but cattle do not linger in the area (Nora Taylor, pers. comm.) Seeds from 5 sites stored at The Berry Botanic Garden (BBG File).

Edward Guerrant, Ph.D.
  • 01/01/2010

Monitor sites to determine population trends. Study general ecology of the species.

Edward Guerrant, Ph.D.
  • 01/01/2010

Collect and store seed from populations across range. Determine propagation and re-introduction protocols.

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Photos
Nomenclature
Taxon Trifolium leibergii
Authority A. Nels. & J.F. Macbr.
Family Fabaceae
CPC Number 4325
ITIS 26268
USDA TRLE
Common Names Leiberg's clover
Associated Scientific Names Trifolium leibergii
Distribution OR, NVNV: Elko CountyOR: Owyhee Uplands (Harney Co.)
State Rank
State State Rank
Nevada S2
Oregon S1
Habitat

Trifolium leibergii grows on steep slopes comprised of dry, shallow soil derived from decomposing volcanic """"tuff."""" Associated species are sparse, but most commonly include Artemisia arbuscula.

Ecological Relationships

Trifolium leibergii begins its growing season fairly early in the spring. If conditions are dry, plants may remain dormant and emerge in subsequent years when conditions are more favorable. Because plants may not emerge in dry years, the task of monitoring populations and tracking population numbers may be difficult. Also, plants may grow close to each other as they grow from the cracks in the """"tuff."""" This makes it difficult to distinguish individuals and to get an accurate count of individuals. From observation however, it appears that populations are relatively stable. New locations are being discovered as the area is searched, so it is possible that many more populations exist (Nora Taylor, pers. comm.).Because the plants emerge early in the spring and complete their life-cycle early, grazing is not a major threat. The habitat that Trifolium leibergii grows on supports little other vegetation and so is not a prime grazing area. Cattle may walk across the area, but they do not linger. There is some threat from trampling and habitat degradation due to the creation of livestock trails (Nora Taylor, pers. comm.).Little is known about the specific ecology of this species. It is believed to be pollinated by a small native bee (Nora Taylor, pers. comm.).

Pollinators
Common Name Name in Text Association Type Source InteractionID
Reintroduction
Lead Institution State Reintroduction Type Year of First Outplanting

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