This one's and oldie, but this thread has allowed me to use it again. A HA!
I had a friend who used to work for the U.S. Air Force. He told me that a few years ago, the government secretly managed to build and successfully send a manned ship to Mars. We actually made contact with the indigenous Martians!
However, the NASA Austronauts were particularly interested in this super-plant with scarlet-orange fronds and a dark brown stalk, called Nimmen. We had been seeing seas of the stuff in long-range pictures, but had not known what it was.
Upon taking samples of the stuff, they discovered miraculous properties to human biology - accelerated healing rate, boosting of the immune system, and an energy boost that made ginseng look like a placebo.
When asked about this wonder-plant, they found that the Martians had no use for it whatsoever, because it did nothing for their physiology. It was in fact a plant that they destroyed regularly as a pest-plant rather than harvested.
When the astronauts asked if they could take some specimens of this wonder-plant home with them, The Martians said yes, but looked at them as if they were daft.
After all, Mars weeds Nimmen.
