The following Participating Institutions are custodians for this species in the CPC National Collection:
New England Wild Flower Society
The conservation of Potentilla robbinsiana is fully sponsored.
Elizabeth J. Farnsworth contributed to this Plant Profile.
Potentilla robbinsiana is a long-lived, dwarf, alpine perennial. The species is endemic to the White Mountains of New Hampshire, and the main population of several thousand individuals clings to one of the most rugged areas of Mount Washington. Although each tiny plant only covers an area 2-6 cm in diameter (a 25 year-old plant is often the size of a quarter), the species has attracted a great deal of attention from botanical collectors and ecologists fascinated by their sometimes frustrating taxonomy, their unusual reproductive biology, and their extreme rarity. Though it was once precipitously close to extinction, the species appears to be bouncing back in the last two decades since it was protected from trampling by hikers and over-collection and since populations have been augmented in the field. As such, the U. S. Fish and Wildlife Service has recently proposed de-listing the species. As stated in the original listing documentation by the U. S. Fish and Wildlife Service (1996), "Robbins' cinquefoil is symbolic of the fragile alpine ecosystem that is now threatened by excessive public use. The species has aesthetic value for many people, as well as scientific and educational value in promoting our understanding of the ecosystem."
Research and Management Summary:
A large number of individuals and institutions have played important roles in both researching and managing for this species.
Robbins' cinquefoil grows as individual compact rosettes that can produce anywhere between 1 and 50 showy yellow flowers. It has hairy, toothed leaves that grow in groups of three leaflets. The solitary, terminal, yellow flowers are about 5-8 mm wide, with five rounded petals and 20 stamens. As many as five rosettes may grow off a single hardy taproot (which grows up to 5 cm deep in the soil), especially where frost-heaving is impacting a plant.
Distribution & Occurrence
- New Hampshire
Potentilla robbinsiana inhabits the exposed alpine zone (1400-1600 meters in elevation) of the White Mountains in New Hampshire. Here, winter winds inhibit insulating winter snows from accumulating, and frost-heaving and rime ice formation are common (Izard-Crowley 1993). The plant grows on cliffs, fellfields, and solifluction terraces with stony, barren, and silty soils derived from erosion of the surrounding bedrock and cobbles of gneiss/schist/quartzite, which contain calcium silicate (Graber 1980, Graber and Brewer 1985, USFWS 1980). Soils are usually moist from frequent precipitation, but are not waterlogged (USFWS 1980).
The species is a poor competitor when crowded, and survives best where the ground is scattered with prostrate or matted vegetation -- an uncommon habitat in the White Mountains. Plants also appear to prefer a more southerly aspect. The two populations of Potentilla robbinsiana occupy somewhat contrasting habitats. The larger population occurs in a gravelly soil, while the other, much smaller population occurs on a west-facing cliff face.
Plants are very sparse in this challenging environment, but associated species may include: Diapensia lapponica, Solidago cutleri, Arenaria groenlandica, Agrostis borealis, Potentilla tridentata, Vaccinium uliginosum, Loiseleuria procumbens, Rhododendron lapponicum, Juncus trifidus, and Carex bigelowii (Crow 1982).
|Potentilla robbinsiana exists at two sites in three populations.
The largest population contains over 14,000 plants (U. S. Fish and Wildlife Service 2001) with 1,500-2,000 flowering individuals (NatureServe 2001), up from a census total of approximately 9,000 plants in 1992 (Izard-Crowley 1993). This population has been successfully augmented through the efforts of the New England Wild Flower Society (NEWFS).
A second population, discovered clinging to a cliff face in Franconia Notch contained less than thirty plants (Bill Brumback [NEWFS] personal communication) and is not considered viable in the long term (NatureServe 2001).
(Another similarly precarious population once found in Franconia Notch has disappeared (Cogbill 1993)).
A new population of plants was reintroduced to Franconia Notch by NEWFS and currently has over 300 plants; it appears to be naturally expanding.
Conservation, Ecology & Research
Over-collecting: Historically, collection by enthusiastic botanists may have reduced the population size by up to half, with over 800 separate specimens placed in herbaria since its
Studies documenting the ecology of the species have led to a fuller understanding of threats to the species and factors, including trampling and plant competition, contributing to its rarity needs (e.g., Graber 1980, Kimball and Paul 1986, Lee 1986). Because the habitat itself is remote, fragile, and challenging, experimental field studies are lacking.
Transplant efforts have met with mixed success. Early attempts (Graber 1980, Fitzgerald et al. 1988, USFWS 2001) showed high mortality in some areas, with adult plants persisting (but little seedling establishment) at others (Kimball 1985). A new, introduced Franconia population of approximately 300 plants appears viable (USFWS 2001). Because seedlings are highly sensitive to frost-heaving, recruitment rates in all populations are low, and it is difficult to predict the long-term persistence of transplanted populations.
Ex situ seed germination and cultivation have been undertaken by the New England Wild Flower Society, Framingham, Massachusetts. Seeds need a period of moist cold in order to germinate well. Germination after treatment with gibberellic acid (a plant hormone) is erratic. Seeds remain viable in seed bank for at least 5-10 years.
The New England Wild Flower Society has developed successful techniques for nursery cultivation and reintroduction of Potentilla robbinsiana. Summer transplants using plants that have been potted in the nursery have shown nearly 100% survival rates.
Likewise, Tom Lee at the University of New Hampshire has devised methods for seed germination and seedling propagation (Lee 1987). More research is needed on the causes of mortality once ex situ plants have been moved to field sites.
To establish four additional self-maintaining transplant populations as called for in the 1980 U. S. Fish and Wildlife Service Recovery Plan, population monitoring protocols were developed and instituted at both populations. Features of microhabitats where the plants preferentially occurred were identified and used to locate unoccupied, potentially suitable habitat. Finally, effective propagation and transplant techniques were developed.
Two-year-old plants germinated from seed were transplanted with the soil media intact in mid-June to early July. Also, each year, a portion of the seed collected for use in transplants is placed in cold storage at the New England Wild Flower Society (Framingham, Massachusetts) to establish a seed bank for the species (USFWS 2001).
If the species is de-listed, as is currently proposed (USFWS 2001), populations must still be monitored for the next five years to determine any impacts of reduced protection.
Volunteer task forces of the New England Plant Conservation Program of The New England Wild Flower Society (Framingham, Massachusetts) and other partners (i.e.., Appalachian Mountain Club staff) monitor populations of Potentilla robbinsiana in New Hampshire.
Impacts of global warming on alpine plant populations.
Studies of herbivore impacts on seedling and adult mortality. Izard-Crowley (1993) reported insect herbivory on 30% of plants surveyed in 1992, with leaf damage caused by aphids and moth larvae.
Hulten, E. 1968. Flora of Alaska and neighboring territories. Palo Alto, CA: Stanford Univ. Press. 1008p.