Yacon: I am Spartacus

I was shaken out of my complacent, smug, yacon breeder's love-in with Frank van Keirsbilck when I received a worrying email from him some days ago.  His yacon seedlings have begun flowering and he is now concerned that a bit of inadvertent cross-pollination with another, unidentified Smallanthus species, may have taken place. It could be that the so-called yacon seedlings are impostor hybrids.

In support of this claim, Frank cites a lemony scent to the flowers and an overall general unease about their "gizz".  That and the fact that he might have transferred the pollen from the unidentified crop wild relative while he was carrying out hand pollinations.

Actually, part of me is delighted by this news - that genes from another species may have been incorporated into yacon's genome.  This is, after all, the reason plant breeders scour the globe, concocting mashups and fiddling with their GIS in order to locate drought, cold, heat and disease tolerance genes in crop wild relatives.

The other half of me is dreading the discovery that, in addition to all those potential benefits, they'll have inherited a less endearing trait common to most other Smallanthus species: the lack of big, fat storage roots.  I fear that some embarrassing and credibility-reducing retraction will have to follow and my reputation amongst my peers will be mud.

My plants have just started flowering and following Frank's revelations I decided to take a closer look.  I can't pick up that lemony scent Frank describes. This could be a result of a phlegmish cold I picked up in Ghent and which seems to have dulled my sense of smell.  Olfactory limitations aside, there are some noticeable differences.

Left to right; white, "morado", "yacon" seedling

Leaf shape is, well, different, more toothy and feral in the seedlings than true yacons.
In fact, they remind me a bit of bearsfoot aka leafcup, Smallanthus uvedalius, a North American wild flower, with a wide distribution - but only a bit. Maybe they look like one or other of yacon's putative parents such as S. macroscyphus or S. siegesbeckius.

Looking at the stems and petioles, both species seemed to have perfoliate leaf bases and winged petioles.  This is the standard white variety on the left; the "yacon" seedling is on the right; the jury could be said to be out on this feature.  I don't happen to have access to a Smallanthus monograph, so I don't know whether the winged petioles are found in several species or are a diagnostic characteristic of yacon, S. sonchifolius. 

One very obvious difference is that ray florets and at least one whorl of disk florets seem to be open at the same time.  You may not be able to see it, but believe me, it's true.  That ain't right for yacon - the literature says so.

Looking more closely, I've noticed another striking deviation from accepted yacon wisdom: damn me if they aren't setting seeds, which is something else Frank has also noticed.  That's not normal yacon behaviour, so I can only conclude that these aren't normal yacons.  As to what they are, I have no idea as yet.  Curiouser and curiouser.



So now when I look back and forth between the true yacons and the lush growth of the  impostors, I recall that memorable scene at the end of the film Spartacus. In a show of solidarity with their leader, the other slaves claim, one by one, that they are Spartacus and in an act of splendid collective suicide are all crucified along the Appian Way.  I doubt whether the A30 would make an acceptable substitute, but Smallanthus does sound a bit like a trident and net-wielding Thracian.  It matters little: if I lift them in due course and find they're all tops and no tubers, they'll soon be pushing up the daisies.

Oca: Where Have All the Flowers Gone?

Over at the 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?

One observation is that big, tall, leafy plants with thick stems seem to come into flower more quickly than those which are smaller.  As usual, there seem to be exceptions to this rule.  Some of my more majestic specimens now have stems of close to a metre in length.  Seedlings with small leaves and short stems, like the one to the right of this picture, seem to be showing no intention of flowering.  I really ought to uproot them immediately, but I'm hesitating; not a case of clemency so much as curiosity: I want to know whether these scrawny runts will perk up when short days come.  Then I'll kill them. Any oca plant that can't enjoy our long balmy summer evenings really has forfeit the right to continued existence and must be catapulted to that heavenly altiplano wherin its ancestors dwell.  Alternatively I might just eat them.

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.

Rambling Radix

Travelling from blessed Cornwall to Belgium in search of flowering ocas sounds a bit excessive. Maybe, but like Robert Johnson, I had ramblin' on my mind.  I blagged my way onto a conference bash in Ghent, then pimped me a seat on Eurostar to get there. This was, perhaps, marginally preferable to riding the rods on the Wabash Cannonball, the default mode of transport for any self-respecting dishevelled hobotanist like me.

The mistaken assumption that the weather was set fair proved to be just that - a mistake. Sandals and no waterproofs compounded the error.  Heavy rain and umbrella-eviscerating winds seemed to have followed us from Cornwall; the latter was, by this time, basking in late summer sunshine.  Tant pis.

After a couple of days of soggy wandering around the city, sampling the chocolate, beer and mayonnaise-smothered French fries, I felt sufficiently emboldened to pursue my real motive for the journey - a visit to Frank van Keirsbilck.  Frank is a plant explorer and enthusiastic disseminator of ethnobotanical delights and he lives a short way from Ghent, in Scheldewindeke.

A twenty minute train ride took me across the pancake-flat East Flanders plain to Scheldewindeke. Large crops of maize and nursery plots of ornamental trees dotted the landscape; the edges of the track were home to vast thickets of frothy-flowered Japanese knotweed.  The Cornwall Knotweed Forum would be apoplectic.

Ambling from the station, I noticed numerous maize cobs infected with Ustilago maydis, corn smut, which produces strangely distorted galls where the cobs should be.  Unlike ergot, these are actually edible and tasty and are considered a delicacy in Mexico, where they are known as huitlacoche.  Apologies for the picture - it was raining heavily and blowing a gale at the time.

In my haste to catch the train, I had forgotten to bring Frank's instructions with me, so I spent some time wandering along his lane, soaking up the ambience, along with the frequent rain showers. I asked for directions from one of his neighbours and, in lieu of English, which everyone supposedly speaks here, we conversed in French. Actually, he said something and I caught the words "cheveux longs" and la-bas", which with the aid of a directing forefinger led me to a pan-tiled, solar panel clad house hidden amongst trees 150 metres or so away.

Frank greeted me and took me straight off for a tour of his bit of Flanders field, which consisted of patches of all sorts of plants in all sorts of combinations all surrounded by heavily cropping fruit trees.  It had been a hard summer, with temperatures up to 35C for several weeks and no rain for a protracted period. This had produced a predictably catastrophic result on some of Frank's precious plants. They had been stunted and shrivelled, some unto death. A particularly sad loss were his ullucos - all gone. A small compensation, perhaps, was a tiny plant of an ulluco variety called 'papa posa' that I had brought with me.  I got it from Frank, who got it in turn from Tom Wagner when he visited Europe last year.  I also gave him a miniscule cutting of one of my favourite chillies, 'rocopica' (said to be Capsicum cardenasii var pendulum) which grows and fruits well in sunless spots.

Back to Frank's garden; the rain had finally returned to Flanders (yes, I'd noticed) and those plants which had survived the full force of the pitiless Belgian sun were beginning to recover following a couple of weeks of steady downpours.

His ocas showed no outward indications of any flowers, although I thought I saw some tiny embryonic buds nestling in the tops of a couple of plants.  At least they were still alive, including a whole load of plants derived from seed I'd sent earlier in the year.

I was particularly taken with his novel crop combination of yacon, mauka and sweetpotato, to which the accompanying picture does not do justice.  Here's the idea: the yacons tower loftily above the intermediately-statured maukas and the whole is finished off by the creeping stems of T65 sweetpotatoes.  All could probably be harvested in one fell swoop and are sufficiently different in appearance to be easily distinguished after lifting:  polyculture just got a whole lot more interesting.

Due to the severity of the summer, the yacons were not as lofty as might have been expected and the other two were commensurately smaller as well, but the idea's certainly worth investigating further.  As for a name for this configuration  - how about los tre amigos, seeing as three sisters and three brothers are already spoken for.

I was also impressed by Frank's Amphicarpaea bracteata plants - one variety was already producing flowers, whereas my own plants remain steadfastly vegetative to date.   Frank told me that the plants have pretty much naturalised in his garden and there were certainly a number of vigorous clumps in various locations.

There were many other delights, but lest I wander completely off task, I'll concentrate on the roots.  As we sat over a leisurely lunch of homemade bread and herb tea, by a slight of hand, Frank produced some potatoes from brown paper bags.  Blight notwithstanding, I do like the outrageous diversity of potatoes one can grow. These definitely looked interesting.

My notepad was a bit damp by this stage, but I think the top variety was called 'puka quitish'; the other I'm not sure of. They're certainly andigena types.

When Frank proffered some Maori potatoes as well, I thought it ill-mannered to refuse.  Judging by the success (not) of our heritage grow-out this year, I feel duty bound to re-home all of them at some stage rather than sacrifice them to death by blight - Phytophthora will be found engraved on my heart.

So I left Frank's with more than I had when I arrived, which is always a pleasant sensation.  I am able to report that no ocas were flowering in this part of  Belgium in late August and I'm hoping that fruitful exchanges of plants and ideas will continue between us in the years to come.  I call that a successful trip.  I took the train back to Ghent and to celebrate, headed out to a convenient eatery to experience another local speciality - wafel met slagroom. Delicious.