The thermal niche of foxtail millet.

<p>At all temperature perturbations it is possible to practice foxtail millet within the area of Shandong. The area in red represents the area in which foxtail can be grown with certainty. The area in white represents the area in cooler adapted varieties of foxtail millet can be grown. Sites represented by black dots are sites where only millet has been recovered from the assemblage. Sites with a black square represent sites where rice has been unearthed in contexts dating to 6000–5000 cal. BC. Sites with an open circle are sites where rice has been unearthed between 5000–3000 cal. BC, however come from poor or undated contexts. Sites with a black triangle represent finds of rice that date between 2600–2000 cal. BC. Sites with a diamond represents sites where rice has been found that post-dates 1800 cal. BC. Map relief from ETOPO1 [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0130430#pone.0130430.ref006" target="_blank">6</a>]; country and province outlines from Natural Earth (naturalearthdata.com).