Sentence:  The Hawaiian dessert most commonly encountered by visitors is haupia. At every commercial luau, a thick and stodgy pudding of cornstarch and coconut milk is cut into squares and served on pieces of green ti leaf. This version is a long way from the original. ... [T]he coconut milk should be thickened with "pia", the Polynesian <WSD>arrowroot</WSD>. ... The most highly regarded "<WSD>arrowroot</WSD>" is West Indian ("Maranta arundinacea"); ... Haupia made with this West Indian <WSD>arrowroot</WSD> was indeed creamier, almost gelatinous, nothing like so solid and pasty, and with a clearer flavor than haupia made with cornstarch. It is worth seeking out <WSD>arrowroot</WSD>, with the caveat that you may not be getting what you expect. 
Meaning of the word marked with <WSD> tags:  A starchy substance obtained from the rhizomes of an arrowroot plant used as a thickener.