Americanized Lens-Podded Hoary Cress Gardens: Bitter Herbs, Bad Soils

Summary: Americanized lens-podded hoary cress gardens better bad, barren, compacted, disturbed soils but their juices, roots and seeds batter crops and livestock.

closeup of lens-podded hoary cress flowers and foliage; Bozeman, Gallatin County, southwestern Montana; Thursday, May 26, 2016, 10:30:12: Matt Lavin, CC BY SA 2.0 Generic, via Flickr

Americanized lens-podded hoary cress gardens apply corklike roots, prolific seeds and rooting rhizomes to adorn ditches, farmyards, fencelines, railways, roadsides and wastelands and ambush croplands, gardens, lawns, orchards, pastures, rangelands and woodlands.

Land invasions bring weed sanctions against the introduced west Asian perennial and against introduced, related Eurasian globe-podded (Lepidium appelianum) and European heart-podded (Lepidium draba) hoary cresses. Alberta provincial, Canadian federal and Arizona, California and Oregon state governments call globe-, heart- and lens-podded hoary cresses, herbaceous mustards in the Brassicaceae family, unwelcome weeds. Alaska, Colorado, Idaho, Kansas, Montana, Nevada, New Mexico, South Dakota, Utah, Washington and Wyoming state governments likewise designate globe- and heart-podded, not lens-podded, hoary cresses weeds.

Hawaii and Iowa state governments enact sanctions against heart-podded hoary cress despite the three species' mustard family relationships with broccoli, cabbage, canola, kohlrabi, radishes and rutabaga.

The bitter herb with eight-year expected life cycles fits club-shaped, dull gray-green, embryonic-leafed, 0.28- to 0.35-inch- (7- to 9-millimeter-) long, 0.09-inch- (2.5-millimeter-) wide cotyledons onto brown-green stems.

The first leaf stages get club-shaped, opposite-arranged foliage with downward-pointing, short hairs on margins and surfaces while lateral roots grow two to three weeks after emergence. The alternate-arranged, gray-green, mature, stalkless, 0.79- to 3.15-inch- (2- to 8-centimeter-) long, 0.12- to 1.18-inch- (3- to 30-millimeter-) wide foliage has heart- to arrowhead-shaped, stem-clasping bases. It includes hairy, irregularly toothed to smooth basal leaf margins and inclines from multi-branched, 7.88- to 19.68-inch- (20- to 50-centimeter-) tall stems atop creeping, extensive roots.

Corklike, thick-barked roots juggle 455 buds and 12.14-foot- (3.7-meter) lengths within the first growing season and 23.62- to 31.49-inch- (60- to 80-centimeter-) yearly increments in growth.

Central-stalked, flat-topped, white inflorescences called racemes keep lens-podded hoary cress, commonly named creeping hoary cress, perennial peppergrass, white top and whiteweed, in bloom April to August.

Lepidium chalepense's (little-scaled Aleppo [seedpod]) perfect, regular flowers, 0.16 to 0.24 inches (4 to 6 millimeters) across, liven 0.19- to 0.59-inch- (5- to 15-millimeter-) long stalks. It maintains one pistil, four 0.12- to 0.16-inch- (3- to 4-millimeter-) long petals, four green-white 0.08- to 0.09-inch- (2- to 2.5-millimeter-) long sepals and six stamens. It optimally nurtures 850 lens- to kidney-shaped, two- to four-seeded, 0.09- to 0.24-inch- (2.5- to 6-millimeter-) long, 0.16- to 0.24-inch- (4- to 6-millimeter-) wide fruiting pods.

Americanized lens-podded hoary cress gardens optimally obtain new plants each growing season from each plant's dry-explosive pods called siliques and from rooted rhizomes and root fragments.

Lens-podded hoary cress, described by Swedish botanist Carl Linnaeus (May 23, 1707-Jan. 10, 1778), optimally produces 3,400 oval, red-brown, 0.08-inch- (2-millimeter-) long, 0.06-inch- (1.5-millimeter-) wide seeds.

Sunlit temperatures between 32.9 and minus 40 degrees Fahrenheit (0.5 and minus 40 degrees Celsius) quicken germination of seeds with three-year in-soil and five-year dry-storage viabilities. Seeding, along with rooting rhizomes at leaf-to-stem attachment nodes and rooting 0.39-inch- (1-centimeter-) long root fragments, remains one of three reproduction means for lens-podded hoary cress. Rhizomes in the top 7.09 inches (18 centimeters) of soil, root fragments at 0.59-inch (1.5-centimeter) depths and seeds sustain ever-expanding land takeovers by lens-podded hoary cress.

The green-leafed, red-brown-seeded, white-flowered ground covers in Americanized lens-podded hoary cress gardens taunt crops and livestock least when tucked into research settings and onto unpopular sites.

Large stand of lens-podded hoary cress (Lepidium chalepense; synonym Cardaria chalepensis) displays an abundance of white-petaled flowers and accounts for common name of whitetop; May 26, 2016, 10:29:04: Matt Lavin, CC BY SA 2.0 Generic, via Flickr

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

closeup of lens-podded hoary cress flowers and foliage; Bozeman, Gallatin County, southwestern Montana; Thursday, May 26, 2016, 10:30:12: Matt Lavin, CC BY SA 2.0 Generic, via Flickr @ https://www.flickr.com/photos/plant_diversity/26667741803/

Large stand of lens-podded hoary cress (Lepidium chalepense; synonym Cardaria chalepensis) displays an abundance of white-petaled flowers and accounts for common name of whitetop; Thursday, May 26, 2016, 10:29:04: Matt Lavin, CC BY SA 2.0 Generic, via Flickr @ https://www.flickr.com/photos/plant_diversity/26667742043/

For further information:

"7. Lepidium chalepense Linnaeus." eFloras > Flora of North America > Flora Taxon.
Available @ http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=242328872

Dickinson, Richard; and Royer, France. 2014. Weeds of North America. Chicago IL; London, England: The University of Chicago Press.

"Lepidium chalepense L." Tropicos® > Name Search.
Available @ http://www.tropicos.org/Name/4105252

Linnaeus, Carl. 1756. "169. Lepidium (chalepense)." Centuria II Plantarum: 23. Upsaliae [Uppsala, Sweden]: L.M. Höjer.
Available via Biodiversity Heritage Library @ http://biodiversitylibrary.org/page/36017988

Weakley, Alan S.; Ludwig, J. Christopher; and Townsend, John F. 2012. Flora of Virginia. Edited by Bland Crowder. Fort Worth TX: BRIT Press, Botanical Research Institute of Texas.