Bushy rock-cress, narrowleaf bittercress
FULL SCIENTIFIC NAME
Cardamine impatiens L.
FAMILY NAME COMMON
FAMILY SCIENTIFIC NAME
Cardamine impatiens is an herbaceous annual or biennial that can grow to be 0.6 m (2 ft.) in height. The stem is erect and glabrous. This plant has numerous leaves (6-20) that are membranaceous. The basal leaves are rosulate and pinnately divided, bearing 3-11 leaflets with rounded lobes. The cauline leaves are also pinnately divided, with sharply toothed or lacerate leaflets. These leaves are sagittate-auriculate at their base, which is an important diagonistic characteristic. The plant blooms from May to August and its white flowers are small, being up to 2.5 mm (0.1 in.) long. The slender siliques (a type of fruit) ripen from May to September and are located on spreading-ascending to erect pedicels. They are 1.5-2 cm (0.6-0.8 in.) long and there are 10-24 seeds in each of them. Page References Fernald 722, Gleason & Cronquist 190, Magee & Ahles 542. See reference section below for full citations.
Cardamine parviflora L. (sand bittercress, C. pensylvanica Muhl. ex Willd. (Pennsylvania bittercress), C. hirsuta L. (hairy bittercress). Cardamine impatiens, C. parviflora and C. pensylvanica all look very similar. The most important distinguishing characteristic is the sagittate-auriculate leaf bases of C. impatiens. These can be seen with the naked eye, but is more clearly visualized with a hand lens. See detail in illustration below.
The seeds of Cardamine impatiens are projected out of the siliques for dispersal. They are probably dispersed over longer distances by flowing water. The small seeds can also stick to clothing and animals, and may be dispersed in this manner as well.
Cardamine impatiens is native to Europe, where it grows well in shady woods and on moist limestone rocks and cliffs. In the United States it is located from Maine south to North Carolina and West to Kentucky. In New England it has been reported in Connecticut, New Hampshire, Vermont and Maine.
HISTORY OF INTRODUCTION IN NEW ENGLAND
Though how Cardamine impatiens was originally introduced into the United States from Europe is not known, the first record of the plant in New England was from Peterboro, New Hampshire in 1916. The plant then appeared in Connecticut, followed by a subsequent spread across Connecticut, and later reports from Massachusetts (1991), Vermont (1992), and Acadia National Park in Maine (1994).
HABITATS IN NEW ENGLAND
Early Successional Forest, Edge, Floodplain Forest, Herbaceous Wetland, River or Stream, Roadside, Vacant Lot, Yard or Garden. Cardamine impatiens can grow in woods with dappled shade, and along shady edges of forest. They also do well in areas that have moist soil.
Cardamine impatiens is easily dispersed due to its seed-shooting ability. It can form dense stands in woodland habitats, and outcompete native species. It has been spreading throughout the northeast and should be watched for.
Documentation required: Herbarium specimen or mounted snippet of the stems showing auriculate leaf bases (see illustration above). Best time for documentation: Summer.
Integrated Taxonomic Information System - Taxonomic information about the species
The PLANTS database - General information and map
BioImages: The Virtual Field-Guide - Images
Fernald, M.L. 1950. Gray's Manual of Botany 8th edition. American Book Company, New York.
Tutin, T.G., V.H. Heywood, N.A. Burges, D.H. Valentine, S.M. Walters and D.A. Webb. 1964. Flora Europaea vol.1. Cambridge University Press, Great Britain.
Franzke, A., K. Pollman, W. Bleeker, R. Kohrt and H. Hurka. 1998. Molecular systematics of Cardamine and allied genera (Brassicaceae): Its and non-coding chloroplast DNA. Folia Geobotanica 33(3):225-240.
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.
Glenn, S.D. and K. Barringer. 2004. Cardamine impatiens L. (Brassicaceae) in New Jersey. Journal of the Torrey Botanical Society 131:257-260.
Magee, D.W and H.E. Ahles. 1999. Flora of the Northeast. University of Massachusetts Press, Amherst.
Marhold, K. 1995. Taxonomy of the genus Cardamine L (Cruciferae) in the Carpathians and Pannonia. Folia Geobotanica and Phytotaxonomica 30(4):397-434.
USDA, NRCS. 2001. The PLANTS Database, Version 3.1. (//plants.usda.gov). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.