This was the winning entry in Freelance Traveller Contest 2008-05.
A small and innocuous-looking plant from a cold world. Recently discovered, its natural beauty and current market rarity make it popular room-dressing for ladies of means. It also has a little secret that is just beginning to leak onto the local grapevine - it appears to be a functioning, natural aphrodisiac.
Unfortunately, the Ice Lily is extremely temperature sensitive and must be shipped in powered refrigeration containers at a temperature of between 260 and 270 Kelvin. Any lower and its flowers die back and it goes into its winter hibernation mode for at least a month, any higher and the plant is killed outright. Since interstellar shipment will take at least a week, the containers also need an integral light source.
Sometimes, individual plants may be shipped in refrigerated transparent display cases for direct-to-customer sale.
Export of the plant is restricted, but not illegal, and an export certificate is needed to take a consignment off its home world.
The BITS 101 Cargoes HazCode label for a small Ice Lily consignment might be:
(where 'pict' indicates a hazard pictogram - "toxic", perhaps, so nobody will eat it).
Owing to the plant's recent discovery and presently-limited distribution, the crew will not be aware of the following details, but optionally one of the passengers might have the information, or a directed search of a medical database will provide it - public net searches will not.
When a plant's temperature rises above 0 C (273 K) and it dies (due to a faulty container, perhaps) it gives off a noxious vapour which, although not having any direct health dangers, has hallucinogenic and hypnotic suggestion-enhancing properties. The vapour is not only airborne, but also condenses onto clothes and surfaces to spread by contact, and may re-evaporate in other areas.
When the vapour is inhaled by a person already under the influence of a mood-lifting drug, it acts as a euphoric/aphrodisiac which, in a controlled environment, can lead to enhanced harmless fun. However, without the mood-lifter the hallucinogen preys upon humanity's darker dreams, enhancing its victims' greatest fears. The ship's doctor may see evidence of a plague, the navigator may be convinced of a misjump, the steward, with a vampire novel under his pillow, might misinterpret a passenger's insomnia - and each victim may become highly suggestible to the authenticity of another's delusion...