Diseased plants for food

Vavilov, in his travels through Japan and India, mentions two different plants that are eaten only when infected, or diseased. One is Zizania latifolia (Chinese wild rice) which, he says, is “grown for its diseased, inflated leaf sheaths”. The other is one of the arrowhead species, Sagittaria trifolia, “grown for its diseased, globular rhizomes”. This triggered a memory, which I’ll get to, of the importance of diseases in the domestication of crops, but first I thought I would try to find out more. ^[1]

Of diseased Sagittaria, there is almost nothing on the internet. I myself used to grow S. latifolia, known to some of the indigenous people of North America as wapato. Disease was never an issue in getting a good harvest.

Food Plants of China, by Shiu-Ying Hu, has some information about Zizania. Gu-hei-sui-jun consists of the enlarged young stems of a swamp grass infected by the fungus Ustilago esculenta, which he calls Zizania smut. “The crop is harvested just before the sporification of the pathogene. A slight sign of black threads visible at the broken surface brings the price down. Before cooking, the shoot must be peeled.” Hu also says that while the diseased plant is harvested from the wild in Jiangsu, it is cultivated in paddies in Sichuan. “In cultivation, the plants seldom flower; the cucumber-like infested shoot harvested before any black vein appears, used as a delicacy.” Hu adds, “the taste and texture is reminiscent of mushroom and bamboo shoot”. Grass and fungus; not surprising, really.

And that’s the memory. Almost everything we know about the domestication of maize suggests that the crucial mutations happened just once. If that is so, how come the effects of those changes were noticed? Would anyone have spotted a single odd plant among populations of wild Teosinte? I doubt it, and so does Hugh Iltis, one of the key scientists to have studied the domestication that resulted in maize. Iltis’ idea, which I was privileged to hear him give in person at a conference, and a brilliant presentation it was too, was that people were cultivating Teosinte. Not for the grain, but for the sugary pith and green seeds. And, perhaps most importantly, for the fruiting bodies of Ustilago maydis! Yes, a different species of the same genus that infects Zizania.

Corn smut, or huitlacoche, is absolutely delicious, the basis of some very interesting Mexican recipes even today, and a great reason to cultivate Teosinte. And if you were cultivating Teosinte, how much easier it would have been to see the single plant that had big, accessible grains on its malformed mutant ears.

Flickr photo by Zampano, used with permission.

Notes:

1. There is a published paper that sounds absolutely fascinating and very relevant, but I cannot get access. I’ll keep trying. Meantime, I would be delighted to receive any further information about plants eaten because they are “diseased”. Not fermented! [↩]

Tagged as: Domestication