Berula erecta (Huds.) Coville
Berula pusilla, Berula erecta var. incisa, Berula incisa, Siella erecta, Sium erectum
Basis for Listing
Although it is very common in other regions throughout the northern hemisphere, in Minnesota, Berula erecta (stream parsnip) is associated with a very specific and narrow range of habitats. It occurs in calcareous and hydrologically active settings, such as margins of small spring-fed streams and pools. Since the habitats are sustained by groundwater aquifers, which can be regional in extent, they can be damaged by development projects many miles away. Activities that could interfere with normal groundwater dynamics, such as large-capacity wells, the dewatering of gravel pits or rock quarries, or deep roadcuts could have a deleterious and irreversible effect on the species and its habitat. As need for water, gravel, and rock continues to increase, these activities are only likely to increase their footprint and potential to impact this and other groundwater dependent species. Invasion by watercress is likely a threat as well. It is likely this species has displaced B. erecta at many sites.
Nearly half of the 29 known locations of B. erecta were documented before 1975. Since that time, during an era of intensive biological surveys, around a dozen new locations have been discovered, suggesting that the species remains rare in the state. The combination of highly specific habitat requirements, increasing threats from population centers as they expand, and low number of known locations contributed to the listing of the species as threatened in 2013.
Berula erecta is a perennial forb that reaches a height of 30-80 cm (12-32 inches). The stem of the plant is erect or reclining and sparsely branched. Leaves are at once pinnately compound, oblong in general outline, with 9-23 leaflets. Leaflets are lanceolate to oblong and serrate or lobed. The upper leaves are commonly lanceolate and deeply incised. The flowers are white, 5-parted and arranged in compound umbels. The fruits are 1.5-2.0 mm (0.06-0.08 in.) long, broadly ovate or circular, and flattened laterally (Gleason and Cronquist 1991; Diggs Jr. et al. 1999). Plant height and the size and shape of leaflets may vary because it is one of several aquatic plant species that change their morphology in response to the flow velocity of the streams where they are found. Not all aquatic species respond similarly to hydraulic stress. In the case of Berula erecta, plants in higher velocity waters tend to be smaller than those in slower waters (Puijalon and Burnett 2004). Despite its scientific name, stems may be either erect or reclining and are usually sparsely branched.
Berula erecta is found in calcareous and hydrologically active habitats at the margins of small spring-fed streams and pools and saturated sedge-derived peat (Dale and Miller 1978). In Minnesota, this includes rivulets in wet seepage meadows and calcareous fens and spring-fed streams in forested ravines. Rarely does the species occur more than a few meters from where spring water flows from the ground. In braided streams in Europe, it tends to lodge in areas of stability where fine sediments overlie coarse sediments, and this preference may hold true at those few sites in Minnesota where it is on the banks of rapidly flowing streams (Bornette and Amoros 1991). Groundwater at the rooting zone of B. erecta is notably cold, oxygen-poor and calcium-rich, maintaining relatively stable temperatures year-round. Stable groundwater temperatures enable such spring-fed streams to flow all winter or perhaps to freeze only during the coldest weeks. For this reason, it is sometimes possible for living, green B. erecta to persist into November or December, when most other plants have senesced and died back to their roots. Plants are usually found in full sun in the more open communities to partial shade in forested landscapes. Associated species include Impatiens capensis (spotted touch-me-not) and Poa palustris (marsh bluegrass).
Biology / Life History
Berula erecta is an aquatic and herbaceous perennial stolon-forming species. Like many aquatic species, it can occur in dense beds. It typically blooms from August through September. Although it can reproduce by seed, it is also a flood tolerant species with high hydraulic resistance and is capable of reproduction from broken fragments that colonize banks by drifting downstream (Cellot et al. 1998). The best time to search for this easily overlooked species is when it is in flower. It is well-adapted to very unusual growing conditions. Because of late summer flowering and its extended photosynthetic season, the ability to identify basal leaves is valuable, as vegetative material may be the only portion visible. Berula erecta is reported to be extremely poisonous and capable of causing death in cattle (Lewis and Elvin-Lewis 1977).
Conservation / Management
This species is rare in Minnesota because of limited habitat. Consideration needs to be given to development projects or other activities that could impact groundwater aquifers or their emergence zones and recharge areas, as B. erecta is closely associated with spring-fed systems.
Best Time to Search
The leaves and growth form of Berula erecta are distinctive and can be recognized from early June through the end of October or until the first frost. The presence of flowers and fruit will facilitate identification and can be expected from early July through the middle of October.
Conservation Efforts in Minnesota
While there have been a few populations documented within the boundaries of parks, there has been little or no conservation effort directed toward this species within the state, and no known conservation plans have specifically addressed the needs of this species.
Derek S. Anderson and Nancy P. Sather (MNDNR), 2018
(Note: all content ©MNDNR)
References and Additional Information
Amaros, G., and C. Bornette. 1991. Aquatic vegetation and hydrology of a braided river floodplain. Journal of Vegetation Science 2(4):497-512.
Cellot, B, F. Mouillot, and C. Henry. 1998. Flood drift and propagule bank of aquatic macrophytes in a riverine wetland. Journal of Vegetation Science 9(5):631-640.
Dale, H. M., and G. E. Miller. 1978. Changes in the aquatic macrophyte flora of Whitewater Lake near Sudbury, Ontario from 1947-1977. Canadian Field-Naturalist 92:264-270.
Diggs, Jr., G. M., B. L. Lipscomb, and R. J. O'Kennon. 1999. Shinners & Mahler's illustrated flora of north central Texas. Sida, Botanical Miscellany No. 16. Botanical Research Institute of Texas, Fort Worth, Texas. 1626 pp.
Gleason, H. A., and A. Cronquist. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. Second Edition. New York Botanical Garden, Bronx, New York. 910 pp.
Lewis, W. H., and M. P. F. Elvin-Lewis. 1977. Medical botany: plants affecting man's health. John Wiley & Sons, New York, New York. 544 pp.
Michigan Natural Features Inventory. 2007. Rare Species Explorer [web application]. Michigan Natural Features Inventory, Lansing, Michigan.
Minnesota Department of Natural Resources. 2005. Field guide to the native plant communities of Minnesota: the prairie parkland and tallgrass aspen parklands provinces. Ecological Land Classification Program, Minnesota County Biological Survey, and Natural Heritage and Nongame Research Program. Minnesota Department of Natural Resources, St. Paul, Minnesota. 362 pp.
NatureServe. 2009. NatureServe Explorer: an online encyclopedia of life [web application]. Version 7.1. <http://www.natureserve.org/explorer>. Accessed 26 June 2009.
Ownbey, G. B., and T. Morley. 1991. Vascular plants of Minnesota: a checklist and atlas. University of Minnesota Press, Minneapolis. 320 pp.
Puijalon, S., and G. Bornette. 2004. Morphological variation of two taxonomically distant plant species along a natural flow velocity gradient. New Phytologist 163(3):651-660.