Welsh onion does not form a true bulb, but rather has a thickened pseudo-stem. Biologically, this species is intended exclusively for the production of green mass.
In the reference
41
varieties
crop Welsh onion,
where this is mentioned in the description.
The Welsh onion lacks the process of true bulb formation characteristic of other species of the genus Allium. The visual thickening at the base of the plant is an elongated pseudo-stem, which in morphological descriptions is often characterized as poorly developed or practically non-existent.
Due to the biological characteristics of the crop, bulb weight and diameter parameters are not applied during variety testing and yield assessment. Excessive thickening of the pseudo-stem or the development of daughter bulbs are considered signs of vegetative propagation and plant tillering, rather than quality characteristics of the produce.
General information about the subject — on the page
Bulb.
Varieties of Welsh onion mentioned in the description
Selection based on the description text, not on official evaluation: these data are absent from registers. For specific variety details, please refer to its profile.