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.