Secondary crop

Secondary crops

Among the cereals, rye (Secale cereale) is derived from wild rye (Secale montanum), a widely distributed Mediterranean species. Rye was originally just a weed growing with wheat and barley, but came under similar selective pressures to the crops. Like wheat, it came to have larger seeds and more rigid spindles to which the seeds are attached, as farmers (intentionally or not) selected for grains that remained on the plant. Weeds such as rye were selected against by killing young or adult plants, separating its seeds from those of the crop (winnowing), or both. Further, wheat is an annual plant, while wild rye is a perennial. At the end of each growing season wheat produces seeds, while wild rye does not, and is thus destroyed when the post-harvest soil is tilled. However, occasional mutants do set seed; they were protected from destruction. Rye has thus evolved to become an annual plant, and in Vavilov's terms a secondary or mimetic crop.