Lepidium densiflorum Schrad.
Common Name: SMALL PEPPERGRASS
Coefficient of Conservatism: *
Coefficient of Wetness: 3
Wetness Index: FACU
Physiognomy: Ad A-Forb

Lepidium densiflorum  flowers and fruits J. Morefield flowers and fruits

Sandy and gravelly disturbed ground (roadsides, clearings, fields, gravel pits, dunes, railroads); shores; spreading to dry open forests (oak, aspen, jack pine). By some authors considered native in eastern North America but introduced in the west; by others thought to be native primarily in the west; by some, to be introduced from Eurasia, and by others to be introduced into Europe. Whatever its history, it was probably not native to Michigan, but is now a widespread weed. The earliest Michigan collection dates from 1861 in Washtenaw Co. By the 1870’s it was noted as “common,” however, unlike L. virginicum, the species was apparently not found by the First Survey (1837–1841).

Often misidentified as L. virginicum. The mature fruit of the latter is scarcely if at all longer than broad and tends to be broadest just below the middle. The fruit of L. densiflorum tends to be slightly longer than broad (oblong-elliptic to obovate), often very slightly broader just above the middle, but the shape differences are subtle. A better character is in the seed: in L. virginicum (at least in our region), the cotyledons are accumbent, so that in a cross-section one sees the round embryo at the end of the flattened, parallel cotyledons, diagrammatically shown as =0; in L. densiflorum, the cotyledons are incumbent, so that a cross-section of the seed appears to have 3 structures in a row: 000.

Locations

Alcona County
Alger County
Alpena County
Antrim County
Arenac County
Baraga County
Barry County
Bay County
Benzie County
Berrien County
Branch County
Calhoun County
Charlevoix County
    Including Beaver Island
Cheboygan County
Chippewa County
    Including Drummond Island
Crawford County
Delta County
Dickinson County
Emmet County
Gladwin County
Gogebic County
Grand Traverse County
Gratiot County
Hillsdale County
Houghton County
Huron County
Ingham County
Ionia County
Iosco County
Iron County
Isabella County
Jackson County
Kalamazoo County
Kalkaska County
Kent County
Keweenaw County
    Including Isle Royale
Lake County
Lapeer County
Leelanau County
    Including Fox Islands
    Including Manitou Islands
Lenawee County
Livingston County
Mackinac County
    Including Bois Blanc, Mackinac, Round Islands
Macomb County
Marquette County
Mecosta County
Midland County
Missaukee County
Monroe County
Montmorency County
Newaygo County
Oakland County
Oceana County
Ogemaw County
Ontonagon County
Oscoda County
Ottawa County
Presque Isle County
Roscommon County
Saginaw County
Sanilac County
Schoolcraft County
St. Clair County
Tuscola County
Van Buren County
Washtenaw County
Wayne County

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 11, 2017. http://www.michiganflora.net/species.aspx?id=661.