Cerastium dubium (Bastard) Guépin
Family - Caryophyllaceae
Stem - Ascending to nearly erect, to 50 cm, often multiple from a cespitose base, glandular-pubescent.
Leaves - Opposite, entire, linear to narrowly lanceolate, sessile, to 3 cm, usually with glandular hairs.
Inflorescence - Dichasial cymes, pubescent with short glandular hairs.
Flowers - Bracts entirely herbaceous. Sepals 5-6 mm, glandular-pubescent, margins hyaline. Petals > sepals, moderatly deeply notched at tip, white. Stamens 10. Styles 3.
Fruit - Capsules straight, cylindrical, 8-11 mm, brown at maturity, dehiscing with 6 apical teeth.
Flowering - March - April.
Habitat - Crop fields, disturbed areas.
Origin - Native to Europe.
Other info. - This species first appeared in Washington in 1966, and was first reported from Missouri in 2017. It is easily distinguished from other Cerastiums, being showier and (usually) with flower centers showing bright yellow from shed pollen. Additionally, leaves are very narrow and styles 3 in number. The plant can form huge populations in alluvial farmland.
Photographs taken near Labadie, Franklin County, MO, 3-31-2012 and 4-12-2016 (SRTurner).