This small hawthorn was first collected in New York in 1868 near Tottenville, Staten Island. It was only collected six more times on Long Island and Staten Island up to July 1919. It was not seen again in New York until 2003 when one small shrub was rediscovered near Kreischerville, Staten Island, a locality where it had been last collected almost 100 years earlier!
There is one existing population in a state park but it is under stress by deer browse and may not be viable. There are six historical occurrences.
One small shrub barely continues to survive on Staten Island.
This shrub has always been very rare in New York but apparently populations have declined on Long Island since no plants have been found in recent decades.
Browsing by deer and inadvertent trampling by humans are threats to the remaining population.
The remaining one shrub needs to be protected from deer and humans by erecting a protective barrier.
Research is needed to figure out the best way to augment the surviving population.
The only known, current record of Dwarf Hawthorn in New York is from a sandy opening in a Staten Island coastal forest. (New York Natural Heritage Program 2010). Open woods and dry slopes (Rhoads and Block 2000). Usually in sandy or rocky ground (Gleason and Cronquist 1991). Sandy or rocky banks and woods (Fernald 1970).
It is currently known from one population on Staten Island with historical records in the Manorville/Yaphank area of Suffolk County. An 1895 specimen has also been identified from Chautauqua County.
This shrub is most common in the southeastern United States from Texas and Oklahoma east to Missouri, Kentucky, Ohio, Pennsylvania, and New Jersey. Its northern limit is reached in New York where it is rare.
Dwarf hawthorn is a slender shrub growing up to 2 meters tall. Its twigs have long (2 to 7.5 cm) sharp thorns, and are slender and soft-hairy when young. The leaves are alternate, toothed, and obovate to elliptic or spatulate, shiny above and hairy on the veins below. They are borne on short (2 to 5 mm) hairy petioles. The flowers have 5 white petals, and are borne singly (or rarely in clusters of 2 or 3). The 5 green, toothed sepals persist at the top of the fruit, which are greenish-yellow or red pomes (Gleason and Cronquist 1991).
This shrub can be identified when it is in leaf and also in fruit.
Having only one (or rarely two or three) flowers per cluster distinguishes Dwarf Hawthorn from all other Crataegus species in New York. Most other Crataegus species are larger in size.
Dwarf Hawthorn flowers in May before the leaves emerge, and the fruits can remain on the shrubs through September.
The time of year you would expect to find Dwarf Hawthorn vegetative, flowering, and fruiting in New York.
Crataegus uniflora Muenchh.
Fernald, M. L. 1950. Gray's manual of botany. 8th edition. Corrected printing (1970). D. Van Nostrand Company, 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.
Little, E.L., Jr. 1979. Checklist of United States trees (native and naturalized). Agriculture Handbook No. 541. U.S. Forest Service, Washington, D.C. 375 pp.
Mitchell, Richard S. 1986. A checklist of New York State plants. Bulletin No. 458. New York State Museum. 272 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
Information for this guide was last updated on: September 6, 2012
Please cite this page as:
New York Natural Heritage Program. 2019. Online Conservation Guide for Crataegus uniflora. Available from: https://guides.nynhp.org/dwarf-hawthorn/. Accessed November 15, 2019.