Radix Root Crops Facebook page, we've been gathering data on when and where oca plants have been flowering this season. No need to be dragged into the social media maelstrom to contribute - you can post comments here on how your ocas are doing. Then again, if you'd like to chip in - please do so.
It certainly appears that, with the right combination of stylar morphs, it is not too difficult to achieve pollination and seed set in Oxalis tuberosa. But first you've got to get the plants to flower. That seems to be a little bit more challenging.
I derive no pleasure from reporting that, with the exception of Ian at Growing Oca's early flush of flowers in June, I seem to be the only person I know who has had flowering ocas so far this year. In this area of the planet, at least. I would be delighted if you, dear reader, would be so kind as to prove me wrong.
Some of my plants have been flowering for several months and are forming pods. Indeed, I have been collecting ripe seeds for some weeks already As flattering as it might be to promote myself as a horticultural genius, I'm really not some sort of oca uber-propagator. No, some other factors must be involved in my success. The question is, which ones?
Another observation is that seedlings seem to flower more profusely and earlier than tuber-derived plants. This could be due to the debilitating effects of accumulated viruses, or a genetic tendency that only surfaces when the plants are grown from tubers - somehow linked to physiological maturity of tuber-derived plants; a similar phenomenon is often found in seedling potatoes versus their tuberous brethren.
Ian at Growing Oca suggests that rather than size, rate of growth might be a contributory factor. Some of his plants started flowering during a period of moist weather and mild temperatures, then the hot weather and water stress set in, the plants were stunted and no more flowers were produced. Could be. I've certainly noticed that flowers on some seedlings seem to abort in the bud stage more readily than others. I haven't the faintest idea why.
If my experience is anything to go by, daylength doesn't seem to be an overriding factor, as some of my plants began flowering way back in June, when days were about as long as they ever get.
My understanding is that in the Andes, oca plants grow, flower and then die back to the tubers: they complete their whole life cycle before harvest occurs. Here, the plants seem to continue growing during declining daylengths until they're zapped by frost. As enjoyable as it is to be harvesting tubers so late in the season, yields are often disappointing. My guess is that very short days, low solar intensity and low temperatures are not conducive to producing bulky crops of tubers. No, we need ocas that tuberise at a more appropriate time of year. Whether flowering, which in potatoes is usually associated with the start of tuber formation, is a similar indicator of incipient tuber development in oca, I don't know. My plants have got so big and lush and tangled, it's virtually impossible for me to tell.
One final observation: I noticed yesterday that one of the self-sown seedlings has, in the axils of its leaves, the first signs of flower buds. Whether or not these will develop and flower before winter comes, I don't know, but it is at least indicative of the possibility of sowing oca seeds directly and standing a chance of securing another seed crop.
So to conclude, my oca flowers haven't gone anywhere - they're still being produced in large quantities. I'm just a tad perplexed that no-one else has been so lucky.