Ornamental jewelweed, Policeman's helmet, Purple jewelweed, Himalayan balsam
FULL SCIENTIFIC NAME
Impatiens glandulifera Royle
FAMILY NAME COMMON
FAMILY SCIENTIFIC NAME
Synonyms: Impatiens roylei Walp.
Impatiens glandulifera is a coarse, herbaceous annual that can reach 2 m (6.5 ft.) in height. The stems are hexagonally angled. The leaves on the lower part of the plant are usually opposite while the upper leaves are whorled. The leaves are lanceolate to lance-ovate in shape, have acuminate tips, and measure 5-15 cm (2-6 in.) in length. The leaf margins are sharply serrate. The pink to purplish (sometimes almost white) flowers are usually in groups of 3 and are borne on long peduncled racemes. They are most numerous towards the top of the plant. The flowers are irregular in shape, having broad petals and a saccate lower sepal with a short, recurving spur. These flowers measure 3 cm (1 in.) in length and appear during the summer. The seeds are contained in capsules that measure 1.25-2 cm (0.5-0.75 in.) in length. The seeds are released explosively when the ripened capsule is disturbed or when it dries out. Page References Bailey 644, Fernald 991, Gleason & Cronquist 362, Holmgren 342, Magee & Ahles 722, Seymour 381. See reference section below for full citations.
Impatiens capensis Meerb. (Orange jewelweed (touch-me-not)), Impatiens pallida Nutt. (Yellow jewelweed (touch-me-not))
Impatiens glandulifera is a prolific seed producer. As is typical of the "touch-me-not" family, its seeds are locally dispersed by the ballistic action of its fruit capsules. The seeds can be dispersed further if they reach moving water, which is not uncommon given the plant's preference for moist areas.
Impatiens glandulifera is native to central Asia, particularly in the Himalayan mountains of India. It is found throughout much of Europe. It has naturalized in California, Oregon, Washington, Idaho, Montana, and also in the northeast and Michigan. In New England it is presently reported from Vermont, Massachusetts, Connecticut and Maine.
HISTORY OF INTRODUCTION IN NEW ENGLAND
Impatiens glandulifera was brought to Europe from its native range in the Himalayas in 1835. It was first noted to have naturalized in Europe in 1855. It is presently found in many countries in continental Europe and throughout the UK. Robinson (1908) did not report the presence of Impatiens glandulifera in the 7th edition of Gray's Manual of Botany. In the eighth edition of Gray's Manual, Fernald (1950) reported that Impatiens glandulifera was "becoming occasionally escaped from cultivation" and was found in Nova Scotia, southern New Brunswick, Quebec, Ontario and northern New England.
HABITATS IN NEW ENGLAND
Early Successional Forest, Edge, Floodplain Forest, Railroad Right-of-Way, Roadside, Wet Meadow, Yard or Garden. Like other jewelweeds, Impatiens glandulifera is found mostly in sites with high soil moisture. It is partially shade tolerant and therefore it can grow in lowland, moist forests. It is commonly found in riparian habitats (along streams) and in roadside ditches.
Impatiens glandulifera is unusually tall for an annual plant, has a fast growth rate and the ability to reseed aggressively (each plant can produce about 800 seeds), enabling it to out-compete native vegetation. Its replacement of perennial vegetation on river banks may lead to increased soil erosion. In addition, Impatiens glandulifera flowers produce a very rich nectar, which in Europe has been shown to attract pollinators away from native plants, reducing their seed set.
Documentation required: A specific photograph of the habit or mounted snippet of the flowers. Best time for documentation: Summer, fall.
Washington State Noxious Weed Control Board General information (including brief control information)
Integrated Taxonomic Information System Taxonomic information about the species
The PLANTS Database General information and map
Washington - King County Noxious Weeds Descriptive information
Bailey, L.H. 1949. Manual of Cultivated Plants. Macmillan, New York.
Beerling, D.J. and J.M. Perrins. 1993. Impatiens glandulifera Royle (Impatiens roylei Walp.). Journal of Ecology 81: 367-382.
Fernald, M.L. 1950. Gray's Manual of Botany, 8th ed. American Book Company, New York.
Gleason H.A. and A.C. Cronquist. 1991. Manual of Vascular Plants of the Northeastern United States and Adjacent Canada. 2nd ed. New York Botanical Garden, Bronx, New York.
Holmgren N.H. 1998. Illustrated Companion to Gleason and Cronquist's Manual. New York Botanical Garden, Bronx, New York.
Chittka, L. and S. Schurkens. 2001. Successful invasion of a floral market. Nature 411: 653.
Magee D.W and H.E. Ahles. 1999. Flora of the Northeast. University of Massachusetts Press, Amherst.
Prowse, A. 1998. Patterns of early growth and mortality in Impatiens glandulifera. In: Starfinger, U.,Edwards, K., Kowarick, I., and Williamson, M. (eds) Plant invasions. Ecological mechanisms and human responses. Backhuys Publishers, Leiden, pp. 245-252.
Pysek, P. and K. Prach. 1995. Invasion dynamics of Impatiens glandulifera - a century of spreading reconstructed. Biological Conservation 74: 41-48.
Robinson, B.J. 1908. Gray's New Manual of Botany, 7th ed. American Book Co., New York, NY.
Seymour, F.C. 1969. The Flora of New England. Charles E. Tuttle Co., Rutland, VT.
Tabak, N.M. 2005. Assessing the invasive potential of Impatiens glandulifera (Ornamental jewelweed) in New England. Masters thesis, University of Connecticut, Storrs, CT.
Tickner, D.P., P.G. Angold, A.M. Gurnell, J.O. Mountford. 2001. Riparian plant invasions: hydrogeomorphological control and ecological impacts. Progress in Physical Geography 25(1): 22-52.
USDA, NRCS. 2001. The PLANTS Database, Version 3.1. (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.