National and local news media reported last week that people in all 50 states have received packets of unidentified seeds in the mail. The envelopes carry a China Post label and Chinese writing. Concern over the unsolicited seed packets initially revolved around the possibility that the seeds are those of invasive plants that could threaten native species, wildlife habitats, and crops in the United States.

On Sunday, the USDA released a report stating that 14 species of common plants have been identified, including lavender, rosemary, sage, morning glory, and cabbage. The unsolicited mailings may be a “brushing scheme,” in which online vendors pay “brushers” to order products and ship them to people who did not order them to make it appear that the vendor has a high volume of sales. Recipients are recommended to avoid handling or planting the seeds and to contact the USDA’s Plant Health Inspection Service (APHIS) at www.aphis.usda.gov.

This bizarre news item prompted me to revis...