Allium fistulosum

Allium fistulosum – Spring onion.

Also known as the Welsh onion or scallions.

Biennial or perennial plants from 30 cm (like chives) up to 1 m high (like leeks).
The bulbs are so thin plants are sometimes described as bulbless.
They slowly form clumps.

The narrow green leaves, and the flower scape are both hollow.
The 2 to 6 leaves are up to to 30 cm long.

Leafless blue-green scapes, are up to 1 m high.
The terminal spherical umbel is up to about 8 cm across.
There can be up to 100 flowers on each scape.
The buds are protected by a large spathe-like bract.

The 6 tepals are green or yellowy-white.
Sometimes the flowers are replaced by small bulbils.

The terms spring onion, green onion, scalllion and shallot are used for young
    onions with green leaves and a bulb under 14 mm across.
These may be A. cepa or other species, cultivars or hybrids.