In eastern North America, Indigenous peoples domesticated several crops that are now extinct. We present experimental data that alters our understanding of the domestication of one of these—goosefoot (Chenopodium berlandieri). Ancient domesticated goosefoot has been recognized on the basis of seed morphology, especially a decrease in the thickness of the seed coat (testa). Nondomesticated goosefoot also sometimes produces seeds that look similar or even identical to domesticated ones, but researchers believed that such seeds were rare (1%–3%). We conducted a common garden experiment and a series of carbonization experiments to better understand the determinants of seed polymorphism in archaeobotanical assemblages. We found that goosefoot produces much higher percentages of thin-testa seeds (mean 50% in our experiment, 15%–34% in free-living parent populations) than previously reported. We also found that cultivated plants produce more thin-testa seeds than their free-living parents, demonstrating that this trait is plastic in response to a garden environment. The carbonization experiments suggest that thin-testa seeds preserve under a larger window of conditions than thick-testa seeds, contrary to our expectations. These results suggest that (1) carbonized, phenotypically mixed assemblages should be interpreted cautiously, and (2) developmental plasticity and genetic assimilation played a role in the domestication of goosefoot.

在北美东部，原住民驯化了几种现已灭绝的农作物。我们提供的实验数据改变了我们对其中一种藜（Chenopodium berlandieri）驯化的理解。人们根据种子形态，特别是种皮（种皮）厚度的减少，认识到了古代驯化的藜。非驯化的藜有时也会产生与驯化的种子相似甚至相同的种子，但研究人员认为这种种子很罕见（1%–3%）。我们进行了常见的花园实验和一系列碳化实验，以更好地了解考古植物组合中种子多态性的决定因素。我们发现，藜产生的薄外种皮种子的比例（在我们的实验中平均为 50%，在自由生活的亲本群体中为 15%–34%）比之前报道的要高得多。我们还发现，栽培植物比其自由生活的亲本产生更多的薄种皮种子，这表明这种性状对于花园环境具有可塑性。碳化实验表明，薄种皮种子比厚种皮种子能在更大的条件下保存，这与我们的预期相反。这些结果表明（1）碳化的、表型混合的组合应该谨慎解释，（2）发育可塑性和遗传同化在藜的驯化中发挥了作用。