purslane (Portulaca oleracea), has capsular fruits with a top that 'pops off', so that the seeds are then exposed to weather and wind. This particular type of capsule is called circumscissile, and for this particular plant is could be that the part that is left below with the seeds functions as a splash cup. I don't know, but it is not unlikely. The little black seeds would then splash out of the cup when a raindrop hits the cup, and disperse further than just normal falling down out of the capsule. (Note to myself, research needed!)
Splash cups are not that common, but also occur in the bird's-nest fungus. While looking up purslane I found out that one plant can produce more than 240 000 seeds per season. Well, it is good it is edible then.
You can read more about purslane and this photo here.
Photo credit (c) Arjo Vanderjagt on Flickr
Species: purslane (Portulaca oleracea, Portulacaceae)