What is it and what should I do about it?
Last spring I planted rhubarb in a large pot. It did well. I made a point of no harvesting any shouts. This spring it came up strong but there is an unexpected large firm bulb-like formation on the top one of the stems that looks like it is made up of small individual clusters/parts colored pink and gray. Are you familiar with this growth?
Baltimore County Maryland
It sounds like you are seeing the beginning of a rhubarb flower--the large unopened bud. It may be fully open today. The flower has a thick stalk and a big flower which serve no purpose for you other than to pull energy from the plant. Therefore, you need to remove it. Tear if off, as you would a rhubarb leaf, if it is small enough. If it's too robust, prune off at the bottom.
Thanks for the information.