Allium sphaerocephalon is a plant species in theAmaryllis family known asround-headed leek,round-headed garlic,ball-head onion, and other variations on these names.Drumstick allium is another common name applied to this species. Some publications use the alternate spellingAllium sphaerocephalum.[2] It is abulbousherbaceousperennial plant.
Allium sphaerocephalon is found in the wild across all parts of Europe except in the northern and western countries (Scotland,Ireland,Netherlands,Scandinavia, and theBaltic States).[3][4] Its native range extends to northern Africa and to western Asia as far east asIran.[5] It is also reportedly naturalised inNew York State in the United States.[6] InEngland it grows wild only in theAvon Gorge so is known locally as theBristol onion.[7]
The species is prized by gardeners because of its striking floral display. The spherical "head" (technically anumbel) is borne on a longscape, up to 50 cm in height, usually in July. It can contain hundreds of deep reddish purple flowers.[5]
Thespecific epithetsphaerocephalon derives from ancient Greek, meaning "spherical head".
Allium sphaerocephalon produces egg-shaped bulbs. Smallbulblets are present under the outer layer of the stem (making the plant potentiallyinvasive when grown in gardens). Flowers are borne on ascape up to 50 cm in height, in a spherical to egg-shapedumbel, 1–6 cm in diameter, tightly packed with many flowers crowded together. The relatively small size of the umbel relative to the height of the stem makes this one of those described as "drumstick alliums". Individual flowers are reddish-purple and are occasionally replaced by bulbils (again making this a potentially invasive species).[3]
^E.g.Mathew, Brian (1978),The Larger Bulbs, London: B.T. Batsford (in association with the Royal Horticultural Society),ISBN978-0-7134-1246-8
^abDavies, Dilys (1992),Alliums : the ornamental onions, London: B.T. Batsford (in association with the Hardy Plant Society),ISBN978-0-7134-7030-7, p. 135
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