The following Participating Institutions are custodians for this species in the CPC National Collection:
New England Wild Flower Society
The conservation of Polemonium van-bruntiae is fully sponsored.
Elizabeth J. Farnsworth contributed to this Plant Profile.
Polemonium van-bruntiae is an herbaceous perennial plant. It has distinctive compound leaves that resemble ladder, which give the plant its common name of Jacob's ladder. Although this attractive plant is sometimes cultivated and sold to gardening enthusiasts, it is rare in the wild throughout its range. Polemonium van-bruntiae inhabits a diverse array of wetland types, including shrub swamps, marshes, lake shores, wooded floodplains, forested swamps, springs and moist roadsides. The reasons for its rarity are somewhat puzzling, because it is not a strict habitat specialist and is widely distributed in the eastern United States and Canada. The most prevalent threat to populations of this plant is habitat conversion, especially when dam construction floods wetlands where it occurs.
Research and Management Summary:
A handfull of research studies have been performed on this and a number of closely related species. Volunteer task forces of the New England Plant Conservation Program (New England Wild Flower Society, Framingham, Massachusetts) periodically monitor populations of this species that occur in New England.
This plant grows to a height of 40-100 cm from a rhizome and produces several alternate, pinnately compound leaves with 15-21 pointed, oval leaflets on short petioles. The blue-purple, bell-like, 2-cm-long flowers make this species unique from other Polemonium species in the east because they have long stamens that are exserted beyond the petals.
Distribution & Occurrence
- New Jersey
- New York
- West Virginia
Polemonium van-bruntiae inhabits a diverse array of wetland types, including shrub swamps, marshes, lake shores, wooded floodplains, forested swamps, springs and moist roadsides. The plant often occurs at elevations above 1000 feet (330 meters), including the Catskill High Peaks, and the Appalachians of western Maryland and West Virginia (Maryland Department of Natural Resources 2002). Farther north in its range, however, it appears to inhabit lowlands; for example, in mountains of Vermont (Thompson 1991) and at its one known extant site in Maine, it occurs at approximately 100 meters in elevation (Johnson and Murray 1988). These sites are typically saturated with seepage water for some period of the year, but not flooded (Thompson 1991). Water at several populations was nearly circumneutral, with pH values ranging from 6.6-6.7 (unpublished data cited in Thompson 1991). The majority of populations in Maryland and West Virginia are associated with limestone bedrock. At least one West Virginia population is associated with a very rich flora indicative of circumneutral wetlands (Mueller 2001). However, it is problematic to identify Polemonium van-bruntiae as a specialist because it is found in a variety of wetlands with a number of generalist species (Thompson 1991).
|Conservatively, there may be as many as 80,000 plants present in approximately 60 native populations in North America.
According to Thompson (1991): West Virginia (19 populations, 20000 stems); Maryland (9 populations, 10000 stems); Pennsylvania (4 populations, numbers unknown; one population destroyed); New York (22 populations, 50000 stems); Vermont (5 populations, 1300 stems); Maine (1 population, 10 stems); Quebec (9 populations, 7000 stems estimated).
Conservation, Ecology & Research
The conspicuous blue flowers of this species appear in June and July. Flowers are protandrous; that is, the large, exserted stamens release pollen before the stigma is receptive. This mechanism may encourage out-crossing in the species. Bees have been observed visiting flowers, and may pollinate the plant, although specific pollination studies have not been done (Thompson 1991, COSEWIC 2001).
Bees have been implicated as pre-dispersal seed predators in another alpine species, Polemonium foliosissimum in Colorado (Zimmerman 1980), but this phenomenon has not been explored in the eastern species. Beattie and Culver (1981) indicate that Polemonium van-bruntiae seed is not ant-dispersed, unlike other species common to rich montane forests of West Virginia.
Extensive long-term studies of reproduction and pollination in related congeners may inform hypotheses about fitness and reproduction in P. van-bruntiae (e.g., Zimmerman 1979, Galen 1983, Zimmerman 1984, Galen and Newport 1988, Zimmerman and Pyke 1988, Gilbert 1998). Seeds appear to require a period of winter dormancy in order to germinate successfully (Brumback 1989). Seeds are reportedly dispersed by winter winds and spring flood waters (COSEWIC 2001).
Phylogenetic relationships of species within the Polemoniaceae have been researched using matK sequencing (Johnson 1996).
The New England Wild Flower Society (Framingham, Massachusetts) has successfully propagated Polemonium van-bruntiae from seed collected in Vermont in 1986 (Brumback 1989). Seed germination was enhanced when seeds were refrigerated over winter. Plants were noted to bloom in the second year of growth. Seedlings were transplanted to two Vermont sites in 1990 and survived during the first year, indicating that ex situ cultivation and reintroduction may be feasible (Popp 1990). Certain private horticultural outlets also distribute the seed of Polemonium van-bruntiae.
Volunteer task forces of the New England Plant Conservation Program (New England Wild Flower Society, Framingham, Massachusetts) monitor populations periodically in New England.
Refined studies of specific habitat requirements of the plant, particularly water and soil chemistry
Studies of factors influencing levels of vegetative versus sexual reproduction in populations
Increased monitoring of populations in West Virginia and Pennsylvania, where populations may be directly threatened by flooding
1997. Portrait of a Rare Plant: Jacob's Ladder Polemonium van-bruntiae. New England Wild Flower Notes. 1, 1: 6.
Beattie, A.J.; Culver, D.C. 1981. The guild of myrmecochores in the herbaceous flora of West Virginia forests. Ecology. 62: 107-115.
Britton, N.L. 1892. Bulletin of the Torrey Botanical Club. 19, 224: 131.
Darlington, H.C. 1943. Vegetation and substrate of Cranberry Glades, West Viriginia. Botanical Gazette. 104: 371-393.
Galen, C.; Newport, M.E.A. 1988. Pollinator quality, seed set, and flower traits in Polemonium viscosum: complementary effects of variation in flower scent and size. American Journal of Botany. 75: 900-905.
Johnson, D.M.; Murray, N.A. 1988. Polemonium vanbruntiae (Polemoniaceae) in Maine. Rhodora. 90, 864: 453-454.
Johnson, L.A. 1996. Monophyly and generic relationships of Polemoniaceae based on matK sequences. American Journal of Botany. 83: 1207-1224.
Rhoads, A.F. 1986. Appropriate Horticulrture. Morris Arboretum of the University of Pennsylvania. 15, 5: 7.
Walker, E.C. 1987. Lost and Found. The Garden Club of America Bulletin. 75, 5: 1-2.
Zimmerman, M. 1980. Reproduction in Polemonium: pre-dispersal seed predation. Ecology. 60: 502-506.
Zimmerman, M. 1984. Reproduction in Polemonium: a five year study of seed production and implications for competition for pollinator service. Oikos. 42: 225-228.
Zimmerman, M.; Pyke, E.H. 1988. Experimental manipulations of Polemonium foliosissimum: effects on subsequent nectar production, seed production, and growth. Journal of Ecology. 76: 777-789.