Sunday, May 7, 2017

North American Horse Nettle Gardens Away From Tobacco and Vegetables


Summary: North American horse nettle gardens keep toxic, weedy nightshades from overrunning corn, tobacco and vegetables and from poisoning cattle and horses.


horse nettle (Solanum carolinense) flowers and leaves; Rosaryville Park, Prince George's County, south central Maryland; Oct. 2, 2014 Fritz Flohr Reynolds (FritzFlohrReynolds), CC BY SA 2.0, via Flickr

North American horse nettle gardens antagonize farmers, gardeners, naturalists, orchardists and ranchers least as ground cover for problematic soils and most as pathogen- and pest-hosting weeds amid corn, tobacco and vegetable crops.
The herbaceous perennial in the Solanaceae family of nightshade, potato-related herbs, shrubs, trees and vines brandishes multiple reproduction means, obnoxiously prickly spines and poisonous solanine alkaloids. The common names apple of Sodom, bull nettle, devil's potato, devil's tomato, sand briar, tread-softly and wild tomato consider native Solanum carolinense's (Carolina nettle) ferocious self-defenses. The native of northern Mexico and of the southeastern United States delivers in autumn concentrated toxins that debilitate cattle and horses more than goats and sheep.
Horse nettle exposes eggplants to verticillium wilt, potatoes to flea beetles, mosaic virus, psyllids, stalk-borers and thrips and tomatoes to leaf spot fungus and mosaic virus.

Elliptical to lance-shaped, 0.39- to 0.47-inch- (10- to 12-millimeter-) long, 0.06-inch- (1.5-millimeter-) wide cotyledons, with pale undersides and shiny green upper-sides, fit onto purplish, short-haired stems.
Embryonic leaves give way to alternate, elliptical, first- and second-stage foliage with short, sparse, stiff hairs and to third-stage lobed or wavy margins and star-shaped hairs. The alternate, dark green, mature, oval to egg-shaped, 2.76- to 5.91-inch- (7- to 15-centimeter-) long, 1.18- to 2.36-inch- (3- to 6-centimeter-) wide leaves have pointed tips. The margins include toothed or two- to five-lobed sides while flattened, prickly, yellow, 0.08- to 0.19-inch- (2- to 5-millimeter-) long spines inundate midribs, stalks and veins.
North American horse nettle gardens juggle prickly spines on floral stalks and prickly spines and rough, star-shaped hairs on stems and foliar midribs, stalks and veins.

Four- to eight-rayed hairs and 0.24- to 0.48-inch- (6- to 12-millimeter-) long yellow spines keep mature, 7.87- to 47.24-inch- (20- to 120-centimeter-) tall horse nettles self-defensive.
Five- to 20-flowered, one-sided inflorescences called cymes, with oldest flowers at the tips, liven prickly, spiny stems one month after leaf-out and two months before fruiting. May- through October-blooming, white to violet flowers each measure 0.59 to 0.98 inches (1.5 to 2.5 centimeters) across, whether perfect lower blooms or male-only upper blossoms. Perfect flowers need one pistil, five 0.24-inch- (6-millimeter-) long stamens with 0.28- to 0.35-inch- (7- to 9-millimeter-) long anthers, five united petals and five united sepals.
Persistent, spiny sepals collectively called calyces offer globe-shaped berries, each 0.35 to 0.59 inches (9 to 15 millimeters) across, protection in North American horse nettle gardens.

Forty- to 170-seeded, yellowing green berries yearly produce 5,000 seeds while 3.28-foot- (1-meter-) long underground stems called rhizomes off 6.56-foot- (2-meter-) deep roots produce new shoots.
Disc-shaped, glossy, smooth, yellow to orange-brown, 0.06- to 0.12-inch- (1.5- to 3-millimeter-) long, 0.05- to 0.09-inch- (1.3- to 2.2-millimeter-) wide seeds quit germinating after 10 years. Horse nettle, described by Carl Linnaeus (May 23, 1707-Jan. 10, 1778), relinquishes 10-year in-soil viabilities above 122 degrees Fahrenheit (50 degrees Celsius) and below 3.94-inch (10-centimeter) depths. Its rhizomes, seeds and toxins sustain Alaska, Arizona, Arkansas, California, Hawaii, Iowa and Nevada state, Canadian and Mexican federal and Manitoba provincial legislation against horse nettle.
Petunia-related North American horse nettle gardens tuck African boxthorn, apple of Peru, buffalo bur, henbanes, jimsonweed, nightshades, tropical soda apple and turkey berry away from wrongdoing.

horse nettle seed: NY State IPM Program at Cornell University (The NYSIPM Image Gallery), CC BY 2.0, via Flickr

Acknowledgment
My special thanks to:
Talented artists and photographers/concerned organizations who make their fine images available on the Internet;
Virginia Polytechnic Institute and State University for superior on-campus and on-line resources.
Image credits:
horse nettle (Solanum carolinense) flowers and leaves; Rosaryville Park, Prince George's County, south central Maryland; Oct. 2, 2014 Fritz Flohr Reynolds (FritzFlohrReynolds), CC BY SA 2.0, via Flickr @ https://www.flickr.com/photos/fritzflohrreynolds/15424318432/
horse nettle seed: NY State IPM Program at Cornell University (The NYSIPM Image Gallery), CC BY 2.0, via Flickr @ https://www.flickr.com/photos/99758165@N06/19067048731/

For further information:
Dickinson, Richard; and Royer, France. 2014. Weeds of North America. Chicago IL; London, England: The University of Chicago Press.
Linnaeus, Carl. 1753. "18. Solanum carolinense." Species Plantarum, vol. I: 187. Holmiae [Stockholm, Sweden]: Laurentii Salvii [Laurentius Salvius].
Available via Biodiversity Heritage Library @ http://biodiversitylibrary.org/page/358206
"Solanum carolinense L." Tropicos® > Name Search.
Available @ http://www.tropicos.org/Name/29602586
Weakley, Alan; 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.


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