Thanks for posting that picture of the seed, Joseph, it was really helpful to me!
At some point early in last year's growing season but after my first plantings of sunroot were several feet tall, I saw your
Mother Earth News column on sunroots, including this bit of "nowhere else on the internet" knowledge:
Sunroots have a reputation for being sterile and not producing seeds. That is because seeds only form if pollinated by an unrelated plant and since most people grow a single clone they do not get seeds. Harvesting seeds from sunroots can also be problematic because goldfinches are extremely effective predators of the seed. I bag the seed heads or harvest them shortly after petal drop. Sunroots growing in a genetically diverse population produce thousands of seeds per plant. I only have to bag a few heads in order to have an abundance of seed.
At which point I went to a Sprout's Market 200 miles from the Whole Foods where I bought my first ones, and bought some more, hopefully different
roots. When all was said and done I had sun roots growing in three different places about fifty feet from each other, with both varieties (well, still living in hope about that) planted at two of the three locations. But they were planted several weeks apart, grew at different speeds, suffered from quite a bit of drought in the most distant location where they didn't get watered, and all-in-all were quite variable in growth. I was pleased to get a reasonable harvest from most of the plants (maybe two meal's worth of decent-sized roots for each knob I planted) but only one of the plants (the one in a five-gallon
bucket in my container garden, planted first and receiving daily attention) formed what looked like decent seed heads. After the plants were done at the end of the season I just clipped those seed heads into a baggie, noting at the time that they didn't have many obvious seeds in them. But not knowing what the seed was supposed to look like, I put them aside for later research.
Well, your pretty picture just now inspired me to pull out my baggie, crumble a seed head, and examine the debris. My conclusion is that there aren't very many seeds in my seed heads -- perhaps ten per seed head, not as robust-looking as yours -- but there are a few. I am of
course open to the likelihood that the seeds I did get are sterile, but I'm going to plant them anyway just for fun.
I left lots of tubers in the ground (if they don't get eaten by burrowers) and saved out more in my fridge (if they don't mold) so I'm looking forward to a lot more plants and a full season of growth this year. I also found some wild sunroots about half a mile from my house, so if I get desperate for some different DNA I can plant those.