Toxicological trivia from October 02, 2014: Cyperus rotundus (coco-grass, Java grass, nut grass, purple nut sedge, red nut sedge,Khmer kravanh chruk[) is a species of sedge (Cyperaceae) native to Africa, southern and central Europe (north to France and Austria), and southern Asia.The root system of a young plant initially forms white, fleshy rhizomes, up to 25 mm in dimension, in chains. Some rhizomes grow upward in the soil, then form a bulb-like structure from which new shoots and roots grow, and from the new roots, new rhizomes grow. Cyperus rotundus is one of the most invasive weeds known, having spread out to a worldwide distribution in tropical and temperate regions. It has been called "the world’s worst weed" as it is known as a weed in over 90 countries, and infests over 50 crops worldwide. In traditional Chinese medicine it is considered:a) The primary qi regulating herb; b) Yang Deficiency; c) Yin Deficiency.

Correct answer: a. Read more in WP.