I’ve noticed that pollen doesn’t seem to mature at the same time for the different tiers of anthers in oca (Oxalis tuberosa) flowers. Sometimes the longer stamens seem to have loose pollen, while the shorter stamens don’t. I spent some time looking at oca flowers under the microscope to see if I could find a pattern. No luck with that, but I did catch a few nice pictures.
Oca flower with petals and sepals removed. This is a short-styled flower, showing two tiers of stamens above the styles.
Close up of the lower tier of stamens and the styles.
Close up of the anthers of the longer (interior) stamens.
Interior stamens, showing pollen grains on the anthers
Oca seeds and tubers are sometimes available in our seed shop.