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Family: Poaceae (grass family)
Common names: Goosegrass, crowsfoot grass, wiregrass, crabgrass, dutch grass, fowfoot grass.
Thai: หญ้าตีนกา Ya tin ka; เยอคุม Yoe-khum (Shan); หญ้าปากควาย Ya pak khwai (Central); หญ้าตีนนก Ya tin nok (Bangkok); หญ้าปากคอก Ya pak khok (Saraburi); หญ้าผากควาย Ya phak khwai (Northern).
Tufted annual grass, stems trailing on the ground or erect; up to 40 cm high; flowering stems with alternate leaves, most located toward the base of the stems. It has a particularly tough root system and is hard to pull out.
Leaves: Fresh green in colour, without hairs; up to 8 mm wide and 15 cm long; flat or folded along central vein (cross-section V-shaped); leaf tip boat-shaped.
Inflorescence: Branched; each flowering stem produces 3-8 flowerheads ('branches') that usually are attached at the tip of the flowering stem, although one or more may be attached lower. Flowerheads 5-10 cm long, 5 mm wide, with two dense rows of flowers.
Origin: The geographical origin is uncertain, but it is considered native to Africa and temperate and tropical Asia.
Introduced: Possibly native. Introduction to new areas in contaminated seed.
Habitat: Most typical of tropics and sub-tropics, but with a worldwide distribution; prefers moist soil, but can tolerate drought.
Spread: By seed; a plant produces on average 40,000 seeds, and these can survive for 2-5 years in the soil. They are dispersed by wind and water, as a contaminant in crop seeds and soils, and attached to animal fur and machinery.
Invades: Crops and disturbed habitats on a wide range of soil types; thrives well in full sunlight, in wet conditions and compacted soil.
Impact: Ya tin ka may occur in virtually any annual crop in the tropics and sub-tropics and also in many perennial crops and pastures. Crop losses due to Ya tin ka have rarely been quantified, but it is frequently among the dominant weed species and can lead to serious crop losses (20-70%, depending on crop system). It is perhaps most conspicuous in annual row-crops such as cereals, legumes, cotton, tobacco and vegetable crops in which it is able to establish rapidly before there is adequate shading from the crop. The weed may cause livestock poisoning and may act as an alternative host for crop pests and diseases.