Last year I picked up starts of Purple Sprouting Broccoli in early Spring at the Berkeley Farmer's Market. It turns out that this variety of broccoli usually needs to overwinter before it forms heads. I had six very tall, leafy plants, and I grew inpatient last summer and fall when no heads formed. I ended up feeding the chickens four of the six plants, however I left two in the ground through the "winter." (We've had an incredibly dry and mild winter this year.)
Much to my surprise, the two plants that have overwintered are now forming purple sprouting heads. This purple broccoli forms many smaller heads all over the plant, as you can see in the following photos:
We picked some of the heads last night and enjoyed them with dinner. The purple heads turn green when they are cooked. The taste was very good!