Americanized Hemp Nettle Gardens: Dense, Hairy, Spiny Ground Cover

Summary: Americanized hemp nettle gardens end ground reflection and surface runoff by establishing dense, hairy, pretty, spiny stands on bad soils and poor sites.

hemp nettle's flowers and leaves; Keila, northwestern Estonia; Friday, Aug. 2, 2013, 21:07: Ivar Leidus, CC BY SA 3.0 Unported, via Wikimedia Commons

Americanized hemp nettle gardens assuage ground reflection and surface runoff on roadsides and wastelands but augment their naturalized niches on croplands, gardens and orchards where their strong scents act as pest repellents.

The Eurasian native annual becomes one of seven herbaceous members in the Lamiaceae family of mint-related herbs, shrubs and trees to bear North American weed designations. Mediterranean sage, not Eurasian catnip or Eurasian motherwort, claims officially unwelcome weed status from the California, Colorado, Nevada, Oregon and, with European sage, Washington state governments. Eurasian ground ivy and henbit and native dragonhead and marsh hedgenettle draw respective sanctions in Connecticut, in Alberta and Manitoba, in Manitoba and in Nova Scotia.

The Canadian and Mexican federal governments enact respective sanctions against European self-heal and, with Alaska state and Alberta, Manitoba and Quebec provincial governments, against hemp nettle.

Notched tips and two basal, pointed lobes fit onto oval, 0.19- to 0.39-inch- (5- to 10-millimeter-) long, 0.08- to 0.19-inch- (2- to 5-millimeter-) wide embryonic leaves.

The embryonic stems go from green below the cotyledons to purple toward soil levels and give way to opposite-arranged, oval, toothed, veined, wire-haired first leaf stages. Mature, opposite-arranged, oval to lance-shaped, 1.18- to 4.72-inch- (3- to 12-centimeter-) long foliage has coarse margins with five to 10 teeth per side and bristle-haired surfaces. Hemp nettle, commonly named bee nettle, brittle-stem hemp nettle, dog nettle and flowering nettle, inclines rough foliage from 0.39- to 1.18-inch- (1- to 3-centimeter-) long stalks.

Slender, strong taproots jumpstart growth with dissolved hormones and nutrients that join dissolved hormones and photosynthates from leaves, stalks and stems in Americanized hemp nettle gardens.

Hemp nettle, also commonly named ironweed, ironwort, Simon's weed and wild hemp, knows mature, 11.81- to 39.37-inch (30- to 100-centimeter) heights on branched, bristle-haired, square stems.

The stems let hemp nettle, scientifically named Galeopsis tetrahit (weasel-like, four-parted), look rough with many downward-pointing, stiff hairs and swollen at leaf-to-stem attachment points called nodes. Their tips manage June to September bloom times for terminal inflorescences, called racemes, on central stalks with same-sized stalklets for perfect, irregular, pink, variegated, white blooms. Flowers 0.39-inch (1 centimeter) across need one pistil, two yellow dots and four stamens on five 0.59- to 0.87-inch- (15- to 22-millimeter-) long, tube-shaped, united petals.

Five spine-tipped, 10-ribbed, 0.28- to 0.43-inch- (7- to 11-millimeter-) long, united sepals occur alongside all petals and stamens and every pistil in Americanized hemp nettle gardens.

Hemp nettle, described by Swedish botanist Carl Linnaeus (May 23, 1707-Jan. 10, 1778), produces 2,800 egg-shaped, mottled gray-brown, 0.12- to 0.16-inch- (3- to 4-millimeter-) long seeds.

Sun-warmed, 0.39-inch (1-centimeter), 0.39- to 1.58-inch (1- to 4-centimeter) and 0.79-inch (2-centimeter) depths respectively quicken germination of self-heal, of hemp nettle and of henbit and marsh hedgenettle. Marsh hedgenettle retains unknown viabilities whereas dragonhead, ground ivy, hemp nettle, henbit and self-heal respectively remain viable 3, 2 to 5, 10, 25 and 5 years. Hemp nettle and its weedy relatives suffer, for shedding seed before crop harvests, as scorned relatives of basil, coleus, lavender, mint, oregano, sage, salvia and thyme.

Americanized hemp nettle gardens of catnip, dragonhead, European sage, ground ivy, henbit, marsh hedgenettle, Mediterranean sage, motherwort and self-heal thrive on sites that thwart nonweedy relatives.

Hemp nettle's spiny calyx lobes and coarse stem hairs stiffen by autumn; Bozeman, Gallatin County, southwestern Montana; Saturday, Oct. 30, 2010, 15:42:58: 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:

hemp nettle's flowers and leaves; Keila, northwestern Estonia; Friday, Aug. 2, 2013, 21:07: Ivar Leidus, CC BY SA 3.0 Unported, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Galeopsis_tetrahit_-_kare_kõrvik_Keilas.jpg

Hemp nettle's spiny calyx lobes and coarse stem hairs stiffen by autumn; Bozeman, Gallatin County, southwestern Montana; Saturday, Oct. 30, 2010, 15:42:58: Matt Lavin, CC BY SA 2.0 Generic, via Flickr @ https://www.flickr.com/photos/plant_diversity/5202209342/

For further information:

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

"Galeopsis tetrahit L." Tropicos® > Name Search.
Available @ http://www.tropicos.org/Name/17600083

Linnaeus, Carl. 1753. "2. Galeopsis tetrahit." Species Plantarum, vol. II: 579-580. Holmiae [Stockholm, Sweden]: Laurentii Salvii [Laurentius Salvius].
Available via Biodiversity Heritage Library @ http://biodiversitylibrary.org/page/358600

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.