Malanga or yautia, also know as tannia, tannier, cocoyam (Xanthosoma Species).
These are names for a very confusing root vegetable (actually a corm, a compressed underground stem) resembling a yam. There are more than 40 species, they are very similar to the related taro or dasheen (Colocasia esculenta), and there are many common names that overlap the 2 vegetables and their various species.
The various species of malanga or yautia, include some of the oldest root crops in the world. It was first cultivated in tropical America, and spread to Africa in the mid 1800s, and is also grown in the Philippines. They are especially popular in Cuba (malanga) and Puerto Rico (yautia).
Malanga has more flavor than most other starchy tropical tubers, and its taste is earthy, and has been described as more like nuts than potatoes.