When I had my first bite of the tam-is many years ago, I find it weird and ask why isn't it sweet. After all, tam-is literally means sweet in the melodic Hiligaynon language.
Tam-is is starchy but its "smoother" compared to kamote and cassava. One can find them during market days especially in inland towns where farming is abundant and crops come in different kinds.
In Iloilo City, the best place to find this rootcrop is at the Jaro Big Market aka Huwebesan - for its market day is Thursday.
It is also what Ilonggos call a variant of a tuber-crop related to the ube, potato, taro and yam, among others, with a collective? scientific name of Dioscorea esculenta, syn.: D. fasciculata.
These are tubers are the enlarged storage tips of a rhizome. The “eyes” are actually buds in nodes, arranged in spiral pattern from the base to the apex of the tuber. Aerial tubers, which are common in yams, are called tubercle. (Source)
Now I don't have the "etymology" for tam-is, but it brings back the childhood memories for most especially those with access to rural goods.
Nowadays, tam-is can be considered as a novelty for those not familiar with it... but to those who grew up with it, it's living the taste of yesteryear.
So have your tried Tam-is?