Thick round stem, often appears stripy on closer examination. Stem firm and filled with pith. Leaf stem loosely 'U' shape with a slight flat top part.
Strongly smells of aniseed, espeically when crushed. Stem round and hollow. Leaf stem round with a slight 'U' at the top and can be hollow which is more noticable towards the base of the leaf stem.
Edible - with Caution
Variable in colour from deep purple to green, hairy, ridged. Stem almost like a bolt with hollow centre. Leaf stem overall a deep 'V' shape with a shallow 'U' on the top. Sap can cause skin irritations especially in bright sun-light. Edible when young.
Stem has a distinctive 'U' shape on one side of the main stem, it is also hollow. The leaf stem is just a smaller version of the main stem, with a 'U' shape at the top and hollow in the middle.
Variable in colour, usually green but can be tinged to fully purple in some specimens (those growing under stress), slight downy. Edge of stem has slight ridges. Leaf stem 'V' shaped with a hollow stem towards the leaf stem base, less so at leaf end.
Distinctive celery smell when crushed. Stem heavily ridged. Leaf stem typical 'celery' shape, shallow 'V' on the top with deep ridges on the bottom.
Stem spotted purple with a 'mouse' smell, unpleasant, not really downy or hairy. Stem round and hollow. Leaf stem round and hollow.
Stem very uneven, with shallow ridges, can be hollow depending on age. Leaf stem uneven and angular, filled with pith.