Wild sweet potatoes are an indispensable ingredient in Tibetan cuisine.  Not only are these roots full of flavor, but they also have excellent nutritional value. When ready to harvest, wild sweet potatoes will be underground, but will have a sprout with leaves that is visible above ground. This sprout identifies the location of the potatoes and allows them to be pulled from the earth. In this riddle, the wild sweet potato's sprout is compared to the lead rope on a female dzo.  And, like the dzo, the sweet potato is central to the livelihood of pastoral Tibetans.