I smoke both. The flowers of lion's tail do the trick, the foliage of blue lotus also works. They will not show up on a drug test. Also, some people say they don't work... They really do, but they don't really blast you off, it's not in your face or anything... I just kind of chill out after a joint of the stuff.
Id go for lotus over lions tail any day, it has some pretty nice effects. Lions tail is just the mildest sedation, no real high to speak of.
Man, I've smoked lions tail and didn't do jack for me. Or..maybe it didn't work since i smoked the extract. I dunno.