Leaves and Centaury IDs

[KeenTeen17]

Any ideas on these leaves. They were found next to a river estuary where lots of Sea Milkwort and Wild Celery was growing - is it just the basal leaves of Celery?

Is there any way to ID between Common and Seaside Centaury. I was under the impression that Seaside had a larger flower and parallel leaves.

[treecreeper]

On the second, Rose's Wild flower Key (revised edition) says the key differences are:

Common centaury:
Stem leaves oval-elliptical
Calyx less than three quarters of the length of the corolla tube
Flowers in dense, forking cymes, not umbel-like

Seaside centaury:
Stem leaves parallel sided, strap shaped, blunt
Calyx more than three quarters of the length of the corolla tube
Flowers in dense, terminal, umbel-like clusters