A native perennial that goes by a confusion of folk names, amongst others:
bell weed, black centaury, black knapweed, bowl weed, bull weed, button weed, churl's head, club weed, crop weed, hard weed, hardhead, hardheads, horse knops, horse knots, iron hard, iron heads, iron weed, knob weed, knot weed, lesser knapweed, loggerheads, nob weed, Spanish buttons, sweeps, tassel.
The thistle-like purple flower heads bloom from June to September and are rated amongst the top 5 wild flowers for nectar production. Not surprisingly then they are a favourite of bees, butterflies (you are likely to see common blues, marbled whites and gatekeepers) and moths (eg six-spotted burnett).
Currently though the few knapweed plants by the pond are just showing their dry, brown seedheads, probably as a consequence of the prolonged drought.
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