Cyperus difformis L.

Angiosperms
Order: Poales
Family: Cyperaceae
Subfamily: -
Genus: Cyperus

Common names: Small flower umbrella plant
Thai names:
Chinese names: 异型莎草 yi xing suo cao
Distribution: Afghanistan, Bangladesh, Bhutan, China, India, Indonesia, Japan, Kashmir, Kazakhstan, Korea, Kyrgyzstan, Malaysia, Myanmar, Nepal, Pakistan, Papua New Guinea, Philippines, Russia, Sri Lanka, Tajikistan, Taiwan, Thailand, Uzbekistan, Vietnam; Africa, SW Asia, Australia, Europe, Indian Ocean islands, Madagascar, Pacific islands. Naturalized in Central, North, and South America.
Image locations: Chiang Mai
Map info: Provinces are highlighted according to phytogeographical areas as used in the Flora of Thailand project.
Additional notes: C. difformis is a weed in rice fields.

Images of Cyperus difformis from Thailand.

Cyperus difformis, Muang Chiang Mai, August

References:
The Plant List
Flora of China
Rice Knowledge Bank