Giant Rhubarb

Our neighbour , Judy had a massive rhubarb plants ( at least six or seven feet across) in the corner of her drive which she regularly encourages us to use. I can't say I have ever noticed before but I see this year it has an enormous seedhead or flower which is the size of a fairly big fist. We've grown rhubarb ourselves in the past but I can't ever recall seeing a seedhead. Evidently it means the plant has 'bolted' (what quaint expression) and the seedhead needs to be removed early on in the season.