Estuary beggar-ticks is part of a confusing array of Bidens species that grow in the estuaries of the Hudson River. Surveying for this species is difficult because bloom time is short and its tidal habitat is available only for a few hours a day during low tide. Consequently we have very little information on the distribution of the species in New York.
One historical population has been rediscovered and two new populations have been found since 1985. Six additional historical populations from the 1930s have not been rediscovered.
Each existing population has only been surveyed once and follow-up survey work needs to be done to understand how these plants are doing in the short term.
This plant was never common in New York with only seven historical records from the 1930s. One of the historical records has been rediscovered and two new populations have been found. This species has always survived at low levels in New York and that trend continues.
This species is threatened by phragmites that has taken over some of the marsh habitat where it grows. More survey work needs to be done to find out if present populations still remain or if phragmites has eliminated their habitat completely. Recreational boating may have some effect on populations as docks and landings are constructed near its habitat.
Phragmites needs to be controlled in and around current populations.
Research into habitat preference could discover why this species is not more common in the large expanses of tidal marshes along the Hudson River.
In New York this species is known only from freshwater tidal mud flats and marshes, associated with Scirpus americana, Scirpus validus, Zizania aquatica, Bidens bidentoides and Sparganium eurycarpum (New York Natural Heritage Program 2007). Estuaries (Fernald 1970). Estuaries (Gleason 1952).
In New York this plant is found only in freshwater tidal marshes and mud flats on the lower Hudson River upstream as far as Dutchess County. Historically it was collected as far north as Albany County.
This plant occurs from Quebec and Ontario through the Maritime provinces and coastal New England States, reaching its southern limit in New York.
Delmarva Beggar-ticks is an annual, opposite-leaved herb of tidal shores and mudflats. It has coarsely-toothed leaves which narrow at the base into slender petioles. Its flower heads are entirely discoid (lacking petal-like ray flowers), about 5 to 15mm wide, and erect. The disk corolla is 4-lobed, and the fruit are achenes. These achenes have awns with antrorse (upward-pointing) barbs along the margins (visible under magnification).
Mature flowering heads are required to positively identify this species.
Bidens laevis and Bidens cernua have a mature disk that is wider than 1.5 cm, 5-lobed disc flower corollas, and fruiting heads that are often nodding. Bidens hyperborea, B. laevis and B. cernua all have sessile leaves and achenes with retrorse (downward pointing) barbs. Bidens cernua has a stem that is soft and usually hispid (B. bidentoides has glabrous stems).
Bidens hyperborea flowers from mid-August through September, and fruits from mid-September into October.
The time of year you would expect to find Estuary Beggar-ticks flowering and fruiting in New York.
Bidens hyperborea var. hyperborea None
All of our Bidens hyperborea are variety hyperborea.
Flora of North America Editorial Committee. 2006. Flora of North America North of Mexico. Vol. 21. Magnoliophyta: Asteridae, Part 8: Asteraceae, part 3. Oxford Univ. Press, New York. xxii + 616 pp.
Fernald, M.L. 1950. Gray's manual of botany. 8th edition. D. Van Nostrand, New York. 1632 pp.
Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York. 910 pp.
Holmgren, Noel. 1998. The Illustrated Companion to Gleason and Cronquist's Manual. Illustrations of the Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York.
New York Natural Heritage Program. 2020. New York Natural Heritage Program Databases. Albany, NY.
Reschke, Carol. 1990. Ecological communities of New York State. New York Natural Heritage Program, New York State Department of Environmental Conservation. Latham, NY. 96 pp. plus xi.
Weldy, T. and D. Werier. 2010. New York flora atlas. [S.M. Landry, K.N. Campbell, and L.D. Mabe (original application development), Florida Center for Community Design and Research http://www.fccdr.usf.edu/. University of South Florida http://www.usf.edu/]. New York Flora Association http://newyork.plantatlas.usf.edu/, Albany, New York
Weldy, Troy W. and David Werier. 2005. New York Flora Atlas. [S.M. Landry, K.N. Campbell, and L.D. Mabe (original application development), Florida Center for Community Design and Research. University of South Florida]. New York Flora Association, Albany, NY. Available on the web at (http://newyork.plantatlas.usf.edu/).
Information for this guide was last updated on: January 13, 2009
Please cite this page as:
New York Natural Heritage Program. 2020. Online Conservation Guide for Bidens hyperborea var. hyperborea. Available from: https://guides.nynhp.org/estuary-beggar-ticks/. Accessed July 8, 2020.