Click the number at the start of a key lead to highlight both that lead and its corresponding lead. Click again to show only the two highlighted leads. Click a third time to return to the full key with the selected leads still highlighted.
1 Heads in dense, usually continuous clusters 2-8 cm long (the inflorescence axis usually completely hidden by the crowded heads); flowering May-Jun; [AL eastwards]
1 Heads in open, interrupted arrays, (5-) 8-20 cm long (the inflorescence axis visible in the interruptions between clusters of heads); flowering Aug-Oct; [s. AL westwards]