The species name honors George Engelmann, 19th century German-born botanist, who became famous for his plant studies in the Rocky Mountains in northern Mexico and the discoverer of this species of spikerush. He was also the first to study American vines in detail and helped the French recover their wine industry by providing fungus-resistant grapevines from the United States (George Engelmann in Wikipedia, accessed 1 May 2009). This plant has only ever been found in a few scattered locations on Long Island and New York City area with one outlier at Kinderhook Lake in Columbia County. No sightings were made between 1946 in 1985 when it was rediscovered at Lake Ronkonkoma on Long Island.
There are only two existing populations with less than 50 plants each. One of them is in an area that is highly developed. There are 11 populations from the late 1800s and early 1900s but about half of these are gone because their habitat has been destroyed. Five of these populations need to be rechecked.
Short-term trends are unknown because the known populations have not been rechecked.
Long-term trends are in decline since six of the 11 known historical locations have been destroyed and only two existing populations are known.
One population is threatened by surrounding development and the alteration of its hydrology and water quality.
A wetland buffer needs to be established to prevent degradation of water quality and to maintain the hydrology of the site.
Research is needed to find the habitat preference for this species in order to augment populations.
The few New York collections of Engelmann's Spikerush have been from pond margins, usually with exposed peaty or mucky substrates (New York Natural Heritage Program 2010). Fresh shores, marshes, disturbed places (FNA 2002). Marshes and wet places (Gleason & Cronquist 1991). Wet sand, peat or mud (Fernald 1970).
There are known locations only in Suffolk County including Fishers Island but this spikerush was originally known from all of Long Island and the Bronx with a disjunct population in Columbia County.
This spikerush occurs across central Canada from Alberta to Ontario and is widespread in the United States from Washington to Maine (historical) south to California and Georgia. It is uncommon in the southern tier of states (and absent from Florida) and in the Northeast where it occurs in a handful of counties from New York, Connecticut, and Massachusetts to western Maine.
Spikerushes are graminoid (grass-like) plants which consist of a simple stem (the leaves bladeless and inconspicuous) with an infloresence of a solitary, many-scaled spikelet at the top. The perianth (sepals and petals), if present, is reduced to (usually 3 or 6) bristles. The base of the style expands into a tubercle, and is usually persistent on the fruit (achenes). Englemann's spikerush may be from 2 to 40 cm tall, the stems often spreading or declining. The distal leaf sheath is persistent, with a tooth up to 0.3mm long. The spikelets are lance-shaped to cylindrical or ellipsoid and 5 to 10 mm long, and the floral scales orange brown to straw-colored with a keeled middle vein except for a green midrib. There may be 5 to 8 perianth bristles, or sometimes none. The achenes are .9 to 1.1 mm long. The tubercle is strongly depressed, triangular, and less than ¼ the height of the achene (FNA 2002).
Specimens with mature fruit (tubercles) are needed for identification.
Eleocharis diandra's spikelets lack bristles and have acute floral scales. E. obtusa, E. ovata, and E. aestuum have bristles which overtop the tubercle and their tubercles are more than 1/4 as tall as the achenes (FNA 2002). Eleocharis has subacute or rounded floral scales, it's bristles (if present) are shorter than the tubercle, and its tubercles are less than 1/4 the height of the achenes.
Fruits first mature in late August and persist to mid-October.
The time of year you would expect to find Engelmann's Spike Rush fruiting in New York.
Engelmann's Spike Rush
Eleocharis engelmannii Steud.
Fernald, M. L. 1950. Gray's manual of botany. 8th edition. Corrected printing (1970). D. Van Nostrand Company, New York. 1632 pp.
Flora of North America Editorial Committee. 2002. Flora of North America, North of Mexico. Volume 23. Magnoliophyta: Commelinidae (in part): Cyperaceae. Oxford University Press, New York. 608 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.
Great Plains Flora Association (R.L. McGregor, coordinator; T.M. Barkley, ed., R.E. Brooks and E.K. Schofield, associate eds.). 1986. Flora of the Great Plains. University Press of Kansas, Lawrence, Kansas. 1392 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.
Maher, R. V., G. W. Argus, V. Harms and J. Hudson. 1979. The rare vascular plants of Saskatchewan. Issued as Syllogeus No. 20. National Museum of Natural Sciences, Ottawa, Canada. 138 pp.
Mitchell, Richard S. and Gordon C. Tucker. 1997. Revised Checklist of New York State Plants. Contributions to a Flora of New York State. Checklist IV. Bulletin No. 490. New York State Museum. Albany, NY. 400 pp.
New York Natural Heritage Program. 2010. Biotics database. New York Natural Heritage Program. New York State Department of Environmental Conservation. Albany, NY.
New York Natural Heritage Program. 2019. New York Natural Heritage Program Databases. Albany, NY.
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
This guide was authored by: Stephen M. Young and Richard M. Ring
Information for this guide was last updated on: January 24, 2012
Please cite this page as:
New York Natural Heritage Program. 2019. Online Conservation Guide for Eleocharis engelmannii. Available from: https://guides.nynhp.org/engelmanns-spike-rush/. Accessed November 20, 2019.