Return of the milk thistle Silybum marianum

 

You've got to love a plant whose Latin generic name is Silybum, more prosaically milk thistle Silybum marianum. I’d never seen it until seven years ago, when a friend asked me to identify ‘a triffid growing in some builders’ rubble in the corner of a field’. 

It was impressive, with a height and spread of over a metre, with beautifully marbled leaves and a corona of spiny bracts around the flowers that was reminiscent of medieval weaponry. 

I brought some seeds home and tried to germinate them, with no success, and must have chucked the contents of the pot onto the compost heap. Now, seven years later, this seedling appeared in the garden. Beautiful foliage, but I’ll be a little apprehensive about the plant when it reaches full size, next year. Meanwhile, the young plant has begun to flower, just before the first frosts of winter arrive. Definitely a plant to handle with care: milk thistle has spiny bracts around the flower heads that look as though they could cause serious pain.

Milk thistle

A few days ago I had a call from a landowner who had unusual, unidentified thistles flowering on the edge of one of their fields. They turned out to be two milk thistles Silybum marianum, easily identifiable by the white variegated veins on their leaves. They are about five feet tall and are native to southern Europe, but have been introduced to many countries. They turn up sporadically in Britin, usually on waste ground, though rarely up here in County Durham. 

The plants are painfully prickly, along the leaf margins and especially on the tip of the bracts that surround the flowers. Milk thistles are biennials and it looks like this is now a small, self-sustaining population. Seeds might have arrived originally in animal feed.

I was first shown one here a couple of years ago, but then it was late in the season and all the flowers had run to seed (see bottom photo). This is the first time I've seen it in flower.