Thickener From the Rhizomes of a Tropical Plant
Puzzle 4 of Alternatives to Plastic Pack
Question is: Thickener From the Rhizomes of a Tropical Plant
and the answer is: ARROWROOT
Word Meaning:
ARROWROOT — (countable, uncountable) Maranta arundinacea from the Marantaceae family, a large perennial herb native to the Caribbean area with green leaves about 15 centimeters long.
Definitions from Wiktionary.