Leptochloa chinensis: Leptochloa chinensis (Synonyms: Poa chinensis, Cynodon virgatus, Eleusine chinensis)

Family: Poaceae (grass family).

Common  names: Chinese sprangletop, Asian sprangletop, red sprangletop.

Thai: หญ้าดอกขาว Ya dok khao (Ang Thong); หญ้าเม็ดงา Ya met nga (Nakhon Ratchasima); หญ้ายางคง Ya Yang khong (Chumphon); หญ้ายอนหู ya-yonhu, หญ้าลิเก (Ya Li Ke).

A strongly tufted, annual or short-lived perennial grass; hollow, slender and erect stems; with glabrous leaves and fibrous roots; sometimes rooting at nodes; 50-100 cm tall.

Leaves: Smooth, linear, 10−30 cm long; ligule an inconspicuous membrane 1−2 mm long and deeply divided into hairlike segments.

Flowers: Loose panicle,  20-60 cm long, with many spike-like slender branches; two rows of spikelets each 2-3.2 mm long, purplish or green and 3-7 flowered.

Fruits/Seeds: Grain is brown, smooth or wrinkled (6-9 mm long); an abundant seed producer.

Origin: Native of tropical Asia.

Introduced as: Native to Thailand, but introduced into uninfested areas in animal feed.

Habitat: Occurs in croplands, wetlands, swamps or streams in open lowland regions of the tropics. It can also grow in heavy or light soils, along streams and watercourses, in marshy grounds, and in upland and lowland rice fields.

Spread: Mainly by seed, but division of rootstocks during cultivation can give rise to multiple plants.

Invades: Vegetables, cotton, corn, soya beans, sweet potatoes, peanuts, bananas and other crops. However, its ability to withstand waterlogged conditions as well as drained, moist conditions makes it a problem weed in rice.

Impacts: In India, densities of L. chinensis at 6 plants/m² resulted in mean yield reduction of rice of 44%. Studies in the Philippines have confirmed that leaf hoppers such as Nephotettix virescens and Recilia dorsalis, which transmit rice tungro bacilliform badnavirus (RTBV) and rice tungro spherical virus (RTSV), feed on weeds such as L. chinensis in fallow fields, providing a pathway to infect the next rice crop. The weed is also an alternative host of the rice blast disease Magnaporthe oryzae and reported to have allelopathic effects on some dicotyledonous crops.