FORT LAUDERDALE — They didn’t crack open and spew toxic gas. They didn’t grow into flesh-eating Venus flytraps.

Those mysterious seeds that thousands of people across Florida and elsewhere found in their mailboxes in packages marked with Chinese characters were tested last week by the U.S. Department of Agriculture.

Despite rumors that they could be agents of bioterrorism, it turns out they’re, well, run-of-the-mill seeds.

Mustard, cabbage, morning glory, mint, sage, rosemary, lavender, hibiscus, and rose were among the varieties identified by the USDA’s Animal and Plant Health Inspection Service.

Testing continues on thousands of samples turned in by recipients, but so far the USDA hasn’t found evidence indicating the deliveries were anything other than a scam by online retailers to pump up e-commerce ratings.

In the so-called “brushing scam,” online merchants send unsolicited packages of inexpensive goods to homes that are then logged by the merchants as verified customers. The scheme makes the sellers look more successful than they actually are.

The USDA is still warning residents not to plant the seeds because some might be invasive or carry seed-borne viruses or other diseases. Recipients should avoid opening the packages and contact their state agriculture regulators for collection.

Alarm over the seeds spread across the nation in recent weeks, prompting warnings from the USDA and state agriculture officials.