common star-of-Bethlehem

O. umbellatum is a perennial herbaceous bulbous plant (geophyte), dying back after flowering, to an underground storage bulb. The following year, it regrows from the often shallow rooted bulbs, which are ovoid with a membranous coat, 15–25 millimetres (1⁄2–1 inch) long and 18–32 mm (3⁄4–1+1⁄4 in) in diameter. The bulbs form multiple leaf-bearing bulbils that soon separate but remain close by. Initially the plant forms 6–10 basal leaves, that arise in tufts from the bulbs. The leaves are grooved (canaliculate), smooth (glabrous) and linear with a white to light green linear midrib on the upper surface, and grow up to 30 centimetres (12 in) long and 8 mm (1⁄4 in) broad. O. umbellatum is scapose, with a glabrous flower stem (scape) that emerges from the leaf tufts later and is about 10–30 cm (4–12 in) in height, tapering at its tip.

The inflorescence bears 6–20 flat star shaped flowers on ascending stems (pedicels), 3–3.5 cm (1+1⁄4–1+1⁄2 in), associated with membranaceous leaflets (bracts), 2.5–3 cm (1–1+1⁄4 in), in an open branching umbrella (umbel) shaped terminal cluster, described as a corymbose raceme. The petal-like perianth is radially symmetric (actinomorphic), which is 1.5–2 cm (1⁄2–3⁄4 in) in diameter, consists of six lanceolate tepals which are white with a green stripe on the underside (outside), 15 mm (1⁄2 in) in length and 5 mm (1⁄4 in) wide. …

A native of most of Europe, North Africa and western Asia, O. umbellatum has been adopted as an ornamental garden plant from where it has escaped and naturalised widely in North America, where it is considered an aggressive noxious weed of lawns, gardens and no-till agricultural land, which can be difficult to eradicate. In Europe its range extends from Ireland and Portugal in the west, Italy in the south, north to parts of France and east to Turkey and the Levant. O. umbellatum prefers damp habitats, being found along rivers, streams, and lower, wet areas of pastures. It is tolerant to shade and soil type.

Ornithogalum umbellatum is thermoperiodic, requiring a cold winter to complete its life cycle. It first appears in early spring as tufts of leaves, prior to flowering (proteranthous), which occurs in late spring (May–June), the leaves fading prior to blooming. It reproduces by its bulbs, which form many offsetting bulbils that can be dispersed by water. Like many bulb plants from temperate regions, a period of exposure to cold is necessary before spring growth can begin. This protects the plant from growth during winter when intense cold may damage it. Warmer spring temperatures then initiate growth from the bulb. O. umbellatum spreads aggressively in clumps by means of these offsets.

Despite the known toxicities, the plant has been described as edible for 2,000 years and incorporated into some traditional regional cuisines (e.g., Turkish) and traditional medicine (e.g., Indian). In Britain, the plant has long been the subject of herbals for its claimed culinary and medicinal properties. This includes drying and grinding the bulbs, or boiling them and baking the flowers into bread. Essences are sold as patent remedies and for aromatherapy, such as Bach flower remedies. Medical authorities advise against ingesting any part of the plant.

Ornithogalum umbellatum requires considerable moisture during winter and spring, but can tolerate summer drought. It can be grown in a woodland garden as semi-shade is preferable. It is hardy to zone 5 UK, 4–9 USDA, and can become invasive. It is produced commercially as an ornamental garden plant. To control invasive tendencies, it is best to plant in a container or an edged area. O. umbellatum may be grown as an indoor plant.

The species epithet reflects the flower formation as an umbel. The plant's many common names include garden star-of-Bethlehem, sleepydick, nap-at-noon, grass lily, summer snowflake, snowdrop, starflower, bird's milk, chinkerichee, ten-o'clock lady, eleven-o'clock lady, Bath asparagus, and star of Hungary. The references to the time of day reflect the opening times of the flowers, opening late and closing at night or in cloudy conditions. The star names indicate the arrangement of the petals and bird's milk is a literal translation of ornithogalum. It has also been called dove's dung, equating it with a plant described in the bible. The name star-of-Bethlehem is shared by a number of species of Ornithogalum, due to the white stellate flowers, and the folklore relating the flower to the biblical star-of-Bethlehem (see In popular culture).