Epilobium parviflorum, a Rare European Introduction along the Niagara River

P. M. Eckel
Res Botanica
A Missouri Botanical Garden Web Site
June 30, 2004

Originally published in New York Flora Association Newsletter 13(2): 3-5. 2002.


Epilobium parviflorum, a Rare European Introduction along the Niagara River –


by Patricia M. Eckel, Buffalo Museum of Science


The Niagara River Gorge is, and has been, host to a dazzling array of both native and exotic plant species throughout the centuries-long history of botanical interest in the area. It offers seven miles of stratified sandstone and dolomite habitats, providing a pattern of both acidic and basic substrates on a variety of steep slopes. There is a patchwork display of shaded pockets of stable, moist black soil with high humus and exposed, sterile crumbling soft shales, with about half of these areas exposed to the west and half to the east.  Transportation corridors span the gorge, now, with a complex of bridges, exposing the region to a rain of propagules of exotic species, some of which are spread by trains and highway vehicles, and some of which escape nearby gardens and yard plantings. In addition, the region is frequented by waterfowl who bring in quantities of seeds and plant parts picked up during their migrations.  There has been a recent proliferation of persistent, exotic taxa among the native flora, brought about, at least in part, by climate factors.  Nowhere is this more apparent than along the two old, west-facing railroad beds near the northern terminus of the gorge, at Lewiston, New York.


There, in what was formerly a relatively barren area of crumbling red shales, a soft, mobile talus derived from the beds has recently developed a veritable jungle of exotic species. The weedy populations have developed in extensive seepage along the dolomite caprock and in its effluent, which flows in the up per ditches that parallel the railroad bed and the gorge wall.


As part of an attempt to describe the vegetation of this habitat and correlate it with other patch communities on both sides of the gorge, I initiated a botanical survey in 2001. Preliminary collections included an Epilobium species that was unfamiliar to me at the time, and not recorded from the Niagara Gorge region. It turned out to be E. parviflorum Schreber. Label Data: USA, New York, Niagara Co., town of Lewiston, upper railroad path at mouth of Niagara River and gorge just south of Artpark in the village of Lewiston; calcareous bedrock with extensive shale-sandstone strata, with Salix eriocephala, S. bebbii, S. interior. P. M. Eckel, coll. Sept. 23, 2001 (BUF).


The only previously reported station for this European species in western New York was from Monroe Co., where it was collected by Robert Wesley (NYFA, 1990, Richard Mitchell, personal communication). For about a century, it had been reported for North America only in the vicinity of New York City (Kings and Queens Counties) and on ballast at Hoboken, New Jersey, by W. Trelease in 1891 (Purcell, 1976); subsequently, it was recorded eight stations in the province of Ontario, Canada, from the counties of Grey, Simcoe and York. The habitats were a clay field, a riparian meadow, mud beside a beaver pond, a wet  cedar-tamarack swamp, stream edges and a “wildlife area” on Toronto Island in Lake Ontario. The three Ontario populations were near to significant bodies of water in the Great Lakes, making it likely that spread of the plant has been by waterfowl, even though seed dispersal in this group is usually by wind. The species was found in Michigan in 1966 and has since spread to several counties there (Voss, 1985).


Epilobium parviflorum has stems with spreading hairs and relatively inconspicuous, red-purple flowers. The horizontally pubescence of the stem can cause the species to be confused with native E.  strictum Muhl. and the Eurasian E. hirsutum L.  Epilobium strictum, however, has entire, nearly linear leaves up to 8 mm wide and the stigma is entire.


Both E. hirsutum and E. parviflorum have leaves much wider than 8 mm, and both are distinctly denticulate with deeply 4-lobed stigmas. Epilobium hirsutum has more conspicuous petals, up to 1 cm long, whereas those of E. parviflorum (as the epithet indicates) are smaller, only reaching a centimeter in length. The leaves of E. hirsutum clasp the stem to halfway around its circumference whereas those of E. parviflora are subsessile.  Examination of other collections made along the Niagara River beach, on the southern boundary of the village of Lewiston, revealed a second collection of E. parviflorum, deposited at BUF, indicating that the species is probably well established along the river. It is most likely also established on the Canadian shores of the river, but this remains to be demonstrated.


Literature Cited:


New York Flora Association. 1990. Preliminary Vouchered Atlas of New York State Flora. Ed. 1. New York State Museum Intsitute, Albany.

Purcell, Nancy J. 1976. Epilobium parviflorum Schreb. (Onagraceae) established in North America. Rhodora 78:785-787.

Trelease, W. 1891. A revision of the American species of Epilobium occurring North of Mexico. Report of the Missouri Bot. Gard.  22:67-117.

Voss, Edward G. Michigan Flora. 1985. Part II. Dicots (Saururaceae-Cornaceae). Cranbrook Institute of Science Bulletin 59.