Several of those who run stalls in one large plant outlet, the Sunhe Beidong flower market, said the local police had called vendors to a meeting and forced them to sign pledges to not carry jasmine; one said she had been instructed to report to the authorities those even seeking to purchase jasmine and to jot down their license plate numbers. (She said she had yet to detect any subversives seeking to buy jasmine at her stall.)

Although some vendors were given vague explanations for the jasmine freeze — that the plant was “symbolic” of those people who wanted to sow rebellion — most people involved in the flower trade have been largely left in the dark about why they should behave with such vigilance, and some professed ignorance of the ban altogether. Thanks to a censored Internet, most Chinese have never heard of the protest calls in China, nor are they aware of the ensuing crackdown.

In the absence of concrete information, fantastic rumors have taken root. One wholesale flower vendor at the Jiuzhou Flower and Plant Trading Center in southern Beijing said he heard the ban had something to do with radiation contamination from Japan. A young woman hawking floral bouquets at Laitai, a large flower market near the United States Embassy, said she was told jasmine blossoms contained some unspecified poison that was killing people. “Perhaps you’d like some white roses instead?” she asked hopefully.

Wu Chuanzhen, 53, a farmer who tends eight greenhouses of jasmine on the outskirts of the city, said other growers had insisted that adherents of Falun Gong, the banned spiritual movement deemed an “evil cult” by the authorities, might use the flowers in their bid to overthrow the governing Communist Party. “I heard jasmine is the code word for the revolution,” she said. Her laughter suggested she thought such concerns were absurd.