As it happens, we know that the “wild wheat” is original to the story because it appears in the oldest reference to Vinland in existence, that of Adam of Bremen, writing in Descriptio Insularum Aquilonis 38 (Gesta Hammaburgensis 4.38) in 1075 CE:
Moreover he (King Sweyn II Estridsson of Denmark) spoke of an island in that ocean discovered by many, which is called Wineland, for the reason that vines grow wild there, which yield the best of wine. Moreover that grain unsown grows there abundantly, is not a fabulous fancy, but, from the accounts of the Danes, we know to be a fact. (trans. Arthur M. Reeves)
None of these suggestions has taken hold, however, on account of the fact that they involve special pleading. We must accept that the Norse identified grapes correctly, but not wheat, and that they were telling the truth about what they found. The recent claim that Spartina patens is the self-sowing wheat is new to me, but not significantly different. According to a posting made to a Facebook ground about Vinland last year, European colonists of the 1600s and 1700s used the plant as fodder for farm animals. It spreads through rhizomes and thus appears to sow itself. Thus, the poster sees this grass as the fodder used by the Norse explorers to feed their cattle over the winter in the Saga of Erik the Red.
However, there are problems with this: The fodder fed to animals in the Saga is identified with grass, not with wheat, so if we wish to make that identification we must explain how the poet could distinguish between wheat and grass only sometimes. This isn’t an insurmountable challenge, and it’s not impossible that explorers would call a New World product by an Old World name. For example, Spanish explorers called turkeys by the word for “peacock.”
The bigger problem, though, is that the specific products Adam and the Sagas allege were found in Vinland are exactly the same products that Europeans assumed were to be found in the Western islands. Isidore of Seville, writing 400 years before Adam, gave the same description we find of “Vinland” when describing the Fortunate Islands:
The Fortunate Islands signify by their name that they produce all manner of good things, as if they were happy and blessed with an abundance of fruit. For suited by their nature they produce fruit from precious trees; grape vines of their own accord clothe the hillsides; instead of grass, crops (i.e., wheat) and vegetables are common. Hence, the error of the Gentiles and of the songs of the poets, which suppose this place to be the same as Paradise because of the fertility of the soil. They lie in the Ocean opposite the left of Mauretania, very near the West, and separated from one another by the sea. (trans. Ernest Brehaut and me)
When Adam describes Vinland, he specifically claims that his version is true and not a “fancy” because he was almost certainly thinking of these legends and how his readers would perceive the claim as being nothing more than a fantasy like the others. However, because the Norse claims appear to carefully parallel European expectations for what the strange islands across the Atlantic were expected to hold, it becomes difficult to argue that the Norse were unique in finding the mythically correct produce on the island just by mistake, unencumbered by cultural expectations.
That leaves us with three possibilities: The first, and least likely, is that it was a coincidence and the Norse had no idea what the common European culture expected from Western islands. The second is that the Norse intentionally lied, just as the sagas say Erik the Red lied about the climate of Greenland in naming the island, in order to cast themselves as the discoverers of the Fortunate Islands and the great land expected to exist opposite the Ocean. The third possibility is that, expecting to find the Fortunate Islands or something like them, they interpreted what they found through the cultural lens of European expectation.
We don’t have enough evidence to distinguish between these, but there is a long tradition of trying. Over a century ago Fridtjof Nansen, for example, identified Adam’s Vinland as a derivative of the Fortunate Isles legend in his In Northern Mists (1911), though Erik Wahlgren dismissed the idea without explanation, while Helge Ingstad discounted the connection on the basis that Norse people were ignorant of Latin literature. More recently, Jerold C. Frakes argued in an article in the Journal of English and German Philology (vol. 100, 2001) that Nansen was right, that Christian-Latin culture suffused Icelandic learning (as, indeed, Snorri’s Edda makes quite plain with its references to the Trojan War) and that scholars essentially are cherry picking by declaring details that match L’anse aux Meadows, the only confirmed Viking settlement in America, to be authentic and those that do not (such as the uniped in ch. 12 of the Saga of Erik the Red) to be false. He concludes:
In any case, however, the literate Icelanders of the thirteenth century, consciously or not, incorporated the medieval Norse occupation of the North Atlantic into a larger political and narrative discourse that did take part in a long-standing European discourse tradition that represented confrontations with non-European geography, and this Norse version of it we now can recognize and identify as Eurocentric.