Holosteum umbellatum L.

Jagged Chickweed

© SRTurner

Family - Caryophyllaceae

Habit - Annual forb.

	Entire plant.
© SRTurner

Stems - Ascending to erect, to 35 cm, unbranched or branched at the base, glabrous or sparsely to moderately pubescent with short, stalked glands, especially toward the base.

	Stems and leaves.
© SRTurner

Leaves - Basal and opposite. Basal leaves short-petiolate, the blades 0.2-3.0 cm long, oblanceolate to narrowly oblanceolate. Stem leaves sessile, fused basally into a sheath, elliptic to ovate or lanceolate, somewhat thickened and sometimes slightly succulent, tapered to short-tapered at the base, angled or tapered to a sharply pointed tip.

	Basal leaves.
© SRTurner

Inflorescence - Terminal, long-stalked umbels, the stalks 0.5-2.5 cm long, ascending to spreading at flowering, becoming downward-angled from the base after flowering, and becoming erect or ascending again at maturity of the fruit, the bracts whorled, minute, herbaceous with thin, translucent margins to completely papery and white to translucent.

	Inflorescence.
© SRTurner

Flowers - Sepals 5, 2.5-4.5 mm long, distinct, lanceolate to ovate, angled to a bluntly or sharply pointed tip, the margins thin and white to translucent. Petals 5, 3-5 mm long, oblanceolate to spatulate, tapered to a stalklike base, irregularly toothed or shallowly several-lobed at the tip, white. Stamens 3-5, the filaments distinct. Pistil with 1 locule, sessile. Styles 3, each with the stigmatic area subterminal or along the inner surface.

	Calyces.
© SRTurner

	Corolla.
© SRTurner

Fruits - Capsules, 4-8 mm long, opening by usually 6 outward-curled teeth. Seeds 35-60, 0.5-1 mm long, oblong, flattened, the surface appearing pebbled or with broad, low papillae, orange to brown, lacking wings or appendages.

	Dehiscent fruits.
© SRTurner

	Infructescence habit.
© SRTurner

Flowering - March - May.

Habitat - Glades, dry forest openings, bluffs, lawns, fields, railroads, open disturbed areas.

Origin - Native to Eurasia.

Lookalikes - Small species of Cerastium and Draba.

Other info. - This small and inconspicuous plant is easily recognized by its jagged white flower petals, and by its peculiar habit of orienting its flowers upward, immature fruits downward, and mature fruits upward. This latter behavior gives the plants a very distinctive appearance. The species is found across the southern 2/3 of Missouri, and in several regions across the U.S.

Holosteum umbellatum was first collected in Missouri in 1950, in Washington County. At the time of Steyermark's publication in 1963, it was known from 13 Missouri counties, and is now widespread in the state. It is probably undercollected, since it completes its life cycle and withers away rapidly each spring.

Photographs taken at Matson Hill County Park, St. Charles County, MO, 3-14-2012, Weldon Spring Conservation Area, St. Charles County, MO, 3-15-2016, Marais Temps Clair Conservation Area, St. Charles County, MO, 4-9-2019, and near Labadie, MO, 4-10-2019 (SRTurner).