This is Alexanders Smyrnium olusatrum flowering near Tynemouth castle at the mouth of the river Tyne, in May. At this time of year the flowers have yet to appear but there is a lot of lush growth in its glossy leaves. The plant is supposed to have been introduced as a pot herb by the Romans and it was widely grown as a spring vegetable for its edible stems and leaves for centuries, until it was replaced by celery . The feral populations that are frequently seen are usually the result of past cultivation.
One of the reasons why it may have fallen out of favour might be this rust fungus, Puccinia smyrnii. It distorts the leaves, causing them to swell, then erupts through the surface and releases spores before they wither. Many of the plants that we saw around Tynemouth castle today were heavily infected.
If I'd been a gardener, growing this plant in my kitchen garden, I'd be very disheartened.
More rust fungi here and here