Plants (10-)20-30(-40) cm; bulbs renewed each year, 1-2 × 1-2.5(-3.5) cm; bulblets numerous. Leaves 4-6(-9); blade with white adaxial stripe, 20-30 cm × 3-5(-8) mm. Scape 1-3 dm. Inflorescences corymbose, (4-)8-20-flowered, flat-topped; bracts to 4 cm. Flowers erect; perianth opening flat or bowl-shaped in sun, closing at night, remaining closed on cloudy days; tepals white with wide green abaxial stripe, lanceolate to oblong-lanceolate, 15-22(-30) × 7-8 mm; stamens: outer 5-7 × 2-3 mm, inner 6-8 × 2-3 mm; filaments simple, flattened; anthers 2-4 mm; ovary ovoid to obovoid, strongly 6-angled, 5-6 mm; style 3-4 mm; lower pedicels 2-6 cm. Capsules oblong-ovoid. 2n = 18, 20, 27, 28, 35, 36, 42, 44, 45, 54, 72, 90, 108. Flowering spring. Roadsides, open forests, waste places, dumps; 0--1500 m; introduced; B.C., N.B., Nfld. and Labr.(Nfld.), N.S., Ont., Que.; Ala., Ark., Conn., Del., D.C., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Miss., Mo., Nebr., N.H., N.J., N.Y., N.C., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis.; Europe; n Africa; Asia; Middle East; expected elsewhere. Planted as a garden ornamental, Ornithogalum umbellatum produces many offsetting bulblets that are transported in soil and can become rampant weeds. Adding to the vegetative vigor of this species may be its aneuploid-polyploid karyology (T. W. J. Gadella and L. van Raamsdonk 1981; L. van Raamsdonk 1984). The flowers are noteworthy for their regularity in opening just before noon and closing again before sunset. Two digitalis-like glycosides, convallatoxin and convalloside, poisonous to humans and livestock, are found throughout the plant, but are concentrated in the bulbs and the flowers (W. H. Blackwell 1990; K. F. Lampe and M. A. McCann 1985; D. G. Spoerke Jr. and S. C. Smolinske 1990).