When the green buds puff up at the tree's twiggy tips, the gardener's inner clock strikes a chord: it's tulip time! Today's Growing on the High Plains will scoop up some hisotry and context for these storied favorites, as their influence spans the globe and the hands of time. Their appeal has always run deep. These thick-petaled protruberances once signified wealth and were treated as tradable tender. But if you scroll back far enough, their power moved economies and pushed markets underground—literally and figuratively (on the "black market").