Berberis vulgaris, common or European barberry, has a long history in Europe. The fruits are edible though picking them from among the spines can shred your hands. Secondly, the plant grows densely, with tough, hard-to-break branches...and those spines. Europeans planted them as fences. (Barbed wire for fencing became available only in the 1870s.) Shrubs take some management but form a good solid fence at very little cost. Barbarry was one of the best shrubs for fencing.
When the New World was discovered and settled, barberry plants were brought over and planted as fencing. And, I suppose, some people made barberry jam.
Meanwhile, across Europe and into the Americas, wheat (Triticum aestivum) was a staple of everyone's diet. When the wheat crop failed, there was widespread famine. Wheat crops can fail for many reasons, but a recurrent scourge, since Roman times, was wheat rust. This pathogenic fungus, genus Puccinia, grows inside wheat plants, cuts off their circulation and kills them, so no wheat matures. The surface of the plant looks red-brown and blotchy, hence the name "rust."
Rust outbreaks recurred and the farmers were unable to stop them. In 1660, farmers in Rouen, France passed a law outlawing the growing of barberry where wheat was grown. Others found that too strange to believe and ignored it, but the French had it right. The dreaded black rust, also called stem rust, Puccinia graminis, has a complex life cycle in which it grows on first one host--barberry--and then moves to another--wheat--and back. If both plants aren't present, it dies out. (But can reinfect wheat from long-distance wind-borne spores).
Note: many plant pathogens have complex life cycles and often, like wheat rust, the alternating hosts have very little in common; barberry is a shrub in the barberry family, Berberidaceae, a Eudicot in the classification of flowering plants, while wheat is a grass (grass family Poaceae) in the quite distant Monocotyledon lineage.
|healthy wheat field|
As midwesterners planted barberry for fencing, wheat rust outbreaks increased in intensity. By 1900 there was general agreement that barberry was wheat rust's alternate host but barberry was so abundant and the cost of removing it so astronomic that action was taken only on a very local level.
|barberry leaves, red ornamental variety|
|big barberry plant|
Common barberry can be found in the United States, too--of course they didn't get it all. It has been expanding since the eradication program ended in 1982. Though there was an enormously successful eradication project a hundred years ago, the threat to wheat remains, hence the comment on each species in the Flora of North America.
Comments and corrections welcome.
Chen, X. 2012. Stem rust update and recommendations link Accessed 3/3/20.
Japanese barberry, Berberis thunbergii DC. Invasive Plants Atlas of the United States. link Accessed 3/3/20.
King, C. 2015. The barberry connection with stem rust. Top Crop Manager link Accessed 3/3/20. Threats from wheat rusts are ongoing.
Roelfs, A.P. Effect of barberry eradication on wheat stem rust in the United States. Plant Disease. Feb. 1982. pp. 177-181. link Accessed 3/1/20. Neat details.
Schumann, G. L and K. J. Leonard. 2011. Stem rust of wheat. APS. link Accessed 3/8/20. Good summary of modern status.
Stem rust and barberry in the Pacific Northwest. link Accessed 3/1/20.
Wenning, B. 2012. Japanese Barberry: An Exotic Invasive Plant Fact Sheet. Ecological Landscape Alliance. link Accessed 3/3/20
Whittemore, A. T. Berberis. Flora of North America. link Accessed 3/1/20.
Kathy Keeler, A Wandering Botanist
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