Short answers, pulled from the story.
Asparagus officinalis is native to Eurasia and grows wild along the western coasts of Europe, from northern Spain to northwest Germany, north Ireland, and Great Britain. It has been cultivated as a vegetable since at least the 1st century AD.
Asparagus contains asparagusic acid, which the body metabolises into volatile sulfur compounds including methanethiol, dimethyl sulfide, and dimethyl disulfide. The smell can appear 15 to 30 minutes after eating and declines with a half-life of roughly four hours. Not everyone detects the odor; some people lack sensitivity due to a single-nucleotide polymorphism in a cluster of olfactory receptors.
White asparagus is produced by mounding soil over the shoots as they grow, blocking all sunlight and preventing photosynthesis. The result is a pale shoot believed to be less bitter and more tender than green asparagus. It is especially prized in Germany, where the season traditionally ends on the 24th of June.
China is by far the largest producer, accounting for 87% of world production. Global asparagus output reached 8.6 million tonnes in 2023.
European settlers brought asparagus to North America by at least 1655. The Dutch immigrant Adriaen van der Donck recorded it in his account of farming in New Netherland, and in 1685 William Penn listed it among crops that thrived in Pennsylvania.
Purple asparagus was originally developed in Italy near the city of Albenga and commercialised under the variety name Violetto d'Albenga. It has higher sugar and lower fibre content than green or white asparagus, and can turn green when cooked due to its sensitivity to heat.