Bulb solitary or clustered, cylindric, rarely ovoid-cylindric, 1--2(--4.5) cm in diam.; tunic white, rarely pale red-brown, membranous to thinly leathery, entire. Leaves subequaling scape, 0.5--1.5 cm wide. Scape 30--50(--100) cm, terete, fistulose, covered with leaf sheaths for ca. 1/3 its length. Spathe 2-valved, persistent. Umbel globose, many flowered. Pedicels subequal, slender, 1--3 × as long as perianth, ebracteolate. Perianth white; segments ovate, 6--8.5 × 2.5--3 mm, apex acuminate, with a reflexed point; inner ones slightly longer than outer. Filaments equal, 1.5--2 × as long as perianth segments, connate at base and adnate to perianth segments. Ovary obovoid, with inconspicuous nectaries at base. Style exserted. Fl. and fr. Apr--Aug. 2 n = 16*.
Bulbs 2–12+, borne on short rhizome, cylindric, 2–5 × 1–2.5 cm; outer coats enclosing 1 or more bulbs, white to light brown, membranous, without reticulation; inner coats white, cells obscure, quadrate. Leaves persistent, 2–6, sheathing lower 1/4–1/3 of scape; blade terete, fistulose, 10–40 cm × 10–25 mm. Scape persistent, solitary, erect, fistulose, inflated in middle, tapering to umbel, (12–)15–70 cm × 8–25 mm. Umbel persistent, erect, compact, 50–100-flowered, globose to ovoid, bulbils unknown; spathe bracts persistent, 1–2, 1–3-veined, ovate, ± equal, apex acute. Flowers narrowly campanulate to urceolate, 6–9 mm; tepals erect, yellowish white, withering in fruit, margins entire, apex acute, outer lanceolate, inner narrowly ovate, unequal; stamens long-exserted; anthers white to yellow; pollen white; ovary crestless; style linear, equaling stamens; stigma capitate, obscurely 3-lobed; pedicel 10–30 mm. Seed coat shining; cells 4–6-angled, ± rectangular.
|Welsh onion, Japanese bunching onion|