The familiar foods included in this custom are: rice, alfalfa, peas, millet, sorghum, chickpeas, fenugreek seeds, sunflower seeds, mustard, buckwheat (kusemet, not to be confused with kusmin – spelt – which is a forbidden cereal grain), cumin, vetch, black-eyed peas, arum, soy, mung beans, lentils, fava beans, lupin beans, poppy seeds, flaxseed, pulse, caraway, hemp seeds, common beans (Phaseolus vulgaris), sesame seeds, lupine seeds, corn, clover seed, and tamarind fruit. Products made from kitniyot – corn flakes, corn flour, and rice cakes, for example – are also included in the custom. Saffron was originally called “karkom” in Hebrew and is included in the prohibition. Turmeric, the Modern Hebrew karkom, is permitted. Mustard and flaxseed are not kitniyot, but the custom is to forbid them because they grow in pods like kitniyot.
Rema writes that it is permitted to eat dill and coriander because they are not kitniyot. Nonetheless, Aĥaronim write that they must be examined well because they often contain wheat (MA, MB 453:13).
There are differing customs regarding peanuts. In Jerusalem and many other places people refrain from eating them (Mikra’ei Kodesh 2:60), but in Greater Lithuania they were customarily eaten. One who does not know whether his family was stringent in this regard may eat them (Igrot Moshe OĤ 3:63).
Potato flour is permitted on Pesaĥ. There is no contention that based on the customary prohibition of kitniyot anything from which flour can be made should be forbidden. Rather, the custom only includes what the great Ashkenazic Rishonim forbade. Since potatoes had not yet arrived in Europe then, they are not included in the prohibition (ibid.).