White potato, taro, and lotus root have similar nutritional profiles. 4 oz. cooked counts as a grain serving for all three foods. Taro root is the most dense nutritionally, while white potato and lotus root are a little less dense. When used as an embellishment, lotus root can be counted as a starchy vegetable at 2 oz., but don’t use more than that. Lotus root is not typically eaten as a full dish but rather as an embellishment in Eastern Asian cuisine, similar to water chestnuts.
Potato is always counted as a grain. Due to its higher natural occuring sugars and position on the glycemic index, it may be triggering for those higher on the Susceptability Scale. There is some evidence to suggest that when potatoes are twice cooked, their glycemic count goes down. The higher you may be on the Susceptibility Scale, the more important it will be to monitor your use of potato as a grain, watching for triggers and disturbance to your sense of food neutrality.