Sunday, 27 November 2011

A Fistful of Ocas

Spurred from my lethargy by the signs of recent vole activity and a couple of mild frosts, I decided to lift two of the volunteer oca seedlings.  I had already received indications that there were tubers to harvest, so I wasn't surprised to discover these beauties.
While not exactly fist-filling in their dimensions, they aren't too bad considering their origins as spontaneous eruptions in the regimented realm of the rocoto bed. Who knows - maybe they would have been even bigger without competition from the chillies and the attacks of the voles.






This is the total yield from the two varieties, minus the numerous stolons and baby tubers chomped by the voles before I stepped in. Not too bad for a couple of young ragamuffins from the wrong side of town.



The Cornish Crest shows a fisherman, a tin miner and an oversized chough, which seems to have flapped in from the Lord of the Rings franchise. I'm wondering whether the miner would be willing to stretch out a hand and display what could, potentially, become another local symbol: a shiny oca tuber.  It does seem perfectly possible that oca might be established as a successful niche market crop here in the far south west, if shorter season varieties can be bred.  I've established (I think) that oca seedlings could theoretically be grown en masse outdoors and selected carefully for relevant traits; I am currently exploring the best ways of ensuring that this happens as soon as possible.  I am also proposing, somewhat immodestly, that the count(r)y's name be changed to Ocarnwall as part of a rebranding exercise culminating in a twinning ceremony with Peru.

After soaring whimsically with the choughs, gravity demands that I return forthwith to the ground and face a few facts. My days as oca's wrinkled retainer may be numbered; this Andean adventive is settling in rather well and seems quite capable of pursuing its own independent destiny with precious little input on my part. If the voles let it.

Thursday, 17 November 2011

I Think, Therefore I Yam

I'm not misquoting the late, great Rene Descartes, natural philosopher and mathematician, whose phrase cogito ergo sum has been spouted ad nauseam by have-a-go intellectuals for years. Nope, that's not what I mean.  Neither am I using the word yam as an obscure verb to describe my penchant for eating in a manner famished, nor as an indication that I am spouting nonsense in an animated fashion. It is true, however, that I can and will do both of these if circumstances demand it.

What I mean is that all right thinking people, gardeners and natural philosophers ought to investigate the edible potential of the Chinese yam (Dioscorea polystachya). This is a member of the great and still thoroughly extant genus Dioscorea, which inludes many other edible species.

The Chinese yam comes from temperate areas of, you guessed it, China, along with Korea and Japan.  It's also found as an introduced (read: highly invasive) plant in the USA and should not be planted in those parts where it is likely to be a problem. It's a dioecious (male and female flowers on separate plants) climber and not unattractive. It's also vigorous, as this picture taken last year at Frank van Keirsbilck's garden shows: estimated height 4 metres. The lack of a suitable pollination partner doesn't bother it one little bit. In lieu of true seeds, the Chinese yam produces large quantities of bulbils, or more correctly, tubercles, in its leaf axils. These drop off and establish new plants, hence its potential as an invasive weed.



My understanding (correct me if I'm wrong) is that the majority of plants under cultivation are male, so true seeds are rarely formed. If and when they do develop, they're probably produced in seed pods that look something like these on  D. caucasica, which I took in Ghent last SeptemberAs well as being consumed as a root crop, it is also used in Traditional Chinese Medicine for numerous complaints.

Strangely, Chinese yams have attracted the attentions of a philosopher of an altogether different ilk: Rudolf Steiner. Steiner, the founding father of Biodynamics, thought very highly of the Chinese yam, due to its unique ability, in his opinion, to store light ether in its roots. According to Steiner, this made its cultivation in Europe essential to maintain human health. He envisaged it replacing the good old spud as a staple, due to the latter's tendency to make both people and animals materialistic. I think he meant the opposite of spiritual rather than an atavistic compulsion to hang around shopping malls.  So what on earth is "light ether"?  To me, all this is not only etheric, but esoteric.  The fact that Usain Bolt, sprinter extraordinary, is supposed to attribute his speed to the Trelawny yams he grew up eating in Jamaica, just adds to the peculiar allure of this plant.  But surely the Trelawny yams aren't  D. polystachya, as some reports I've seen suggest, but D. cayensis. 

Image courtesy of Dr Markus Heyerhoff
The Germans seem to have taken Steiner at his word and are now growing the Lichtwurzel (light root) on a limited scale, particularly in the Bodensee region.  Cultivation practices look somewhat elaborate, involving greenhouses and wooden boxes.  Several companies are now marketing the roots and products derived from them.

I contacted Dr Tobias Hartkemeyer at the University of Kassel, located in the raccoon heartland of Germany, where they have been running a research and development project on the Chinese yam: Lichtyams.  I was keen to know whether they had been able to breed any new varieties. Tobias told me he had managed to get a female plant, but this had failed to thrive and he has been unable to produce any true seed so far.

The young shoots resemble those of black bryony, (Tamus communis) the only native British climber in the same family, the Dioscoreaceae. This seems to occur in every hedgerow hereabouts and has attractive glossy leaves and in the autumn, on female plants, bright red berries.  I really like black bryony, but confusing the roots of the two species is the kind of mistake best avoided. Black bryony's roots, yam-like in appearance though they may be, are powerfully irritant and likely to send the diner on a trip to the local hospital.   Luckily, perhaps, the bryony emerges many weeks earlier than the yam and is unlikely to be confused with it.  I do wish the yam showed the same early growth as the bryony, though - it might yield much better.

I'm no stranger to the Chinese yam, having grown it several times in the past, but, if I'm honest, I've hardly ever eaten it. This is probably a shame as it really is supposed to have beneficial effects on one's intellectual, cognitive and spiritual development - according to Steiner that is. It's also very tasty, something which tends to have a greater influence on my choice of food than considerations of continuing spiritual evolution. The biggest intellectual stimulus I have had from from growing it has always occurred as I attempt to figure out how to extract the long, thin, brittle roots from the soil without breaking them.  As you normally have to wait several years before they reach a harvestable size, they also provide you with ample opportunity to develop reserves of patience.


So with all this in mind, I got myself some yam bulbils - two varieties, species even, described as Dioscorea batatas and Dioscorea japonica. These names are doubtless obsolete synonyms which some obliging taxonomist will delight in pointing out to me in due course. On the left are the somewhat smaller bulbils of D. batatas, on the right those of D. japonica.





I'm not much of a party animal, but it's often possible to pick up a few plastic cups at such events; these make serviceable pots for long rooted plants, at least in the early stages of development. Judging by the appearance of what might be politely described as finger-like protuberances from the bottoms of these cups, potting on is now required. My finger is on the right, in case you're confused. The only discernible difference I can see between the two types (species?) is the greater vigour and precocious bulbil development on the D. japonica plants.


Some American polyculture enthusiasts have abandoned the shovel and are now harvesting the yam bulbils as the main food instead.   The 'yamberries' as they are calling them, seem to yield very well in their climate in New England  giving 3-4 US gallons per plant (I think that's around 12-15 litres) in Holyoke MA.  They're certainly miniscule compared to the the fist size ones produced by the air potato, D. bulbifera, but they seem to make up for this by being produced in large quantities. Lightly toasted on a skillet, or in the oven, they are apparently very good eating. A root crop that doesn't require digging - is there no end to the diverse talents of Dioscorea polystachya?

This is an intriguing plant, with delicious roots and all sorts of associated mystique, half-truths and misinformation.  Aside from the necessity of mining the roots rather than harvesting them, the main problem, in our climate at least, is their late emergence in the spring and subsequent slow maturity. If plants of different sexes can be located, it might be possible to set up a Dioscorea dating agency and breed varieties that are better adapted to our climate.  There are, apparently, numerous sorts found in China, with varying shape, size and number of roots.  So, to any Chinese yam enthusiasts who have male and female plants in their possession, Radix awaits your call.

Monday, 7 November 2011

A Profusion of Pods

The mild weather over the past few weeks has led to a bumper crop of oca pods. There are many hundreds, if not thousands of them adorning my plants at the moment.  It may be a bit optimistic to harvest them all before frost strikes, but I'm going to give it my best shot.  There's no way that bagging them individually can be achieved, so I'm just gathering those that are close to ripening and storing them as described previously; it seems to work.  I'm not the only one experiencing success either - Ian at Growing Oca reports similar success, as does David Taylor, who has been contributing to a discussion about oca seed production on the Radix Facebook Page.



Here's an oca tuber from one of last year's seedlings, looking plump and well developed.









The flip side - literally - tells another story: vole damage.  Not content with eating fully formed ones, they also enjoy severing the stolons to which the developing tubers are attached.  In addition to this outrage, they've conducted some impressive pumpkin carving on our squashes, many of which are scarred by hundreds of tiny incisor marks. Ah, the joys of wildlife gardening.



While I was collecting the pods from the volunteer seedlings, I couldn't resist tunneling beneath the surface, just like the voles.  And this is what I found - a quite impressive cluster of tubers, all things considered.  So it's possible for oca seedlings to appear spontaneously, flower, produce seeds and tuberise - all within one growing season.  I think this is what they call progress.

Tuesday, 1 November 2011

Who Tampered With My Yampah?

I have a guilty secret. You're looking at it, or rather, them. Magnifying glasses at the ready - these are my yampah roots. I've been debating for several months as to whether I should reveal them in all their maddeningly minute glory. That time has now arrived.

Although yampah roots are spoken of very highly as a wild food, this rate of growth really doesn't bode well for their general productivity as a garden crop.  Let's just say the potato can lie in its bed a little longer without fear of being usurped.

As so often follows failure, a period of doubt and self-recrimination ensued. Was it the compost, the temperature, transplanting shock? Insect damage perhaps? Something or someone was to blame. Maybe I'm an even less competent horticulturist than I ever realised. I have had them stashed in some vermiculite, hidden from view, while pondering on all of this.

Then last night, I was idly perusing a document from the USDA Forest Service on a related yampah species, Perideridia erythrorhiza, when I came across this quote:

Work in the greenhouse indicates that juveniles will senesce 8-12 weeks after emerging, even if kept well watered, and will not flower the first year. During this early period of growth, a single small tuber 1cm or less is developed, which then remains dormant until the following spring. 

That's it. That's exactly what happened.

So roast yampah roots won't be on the table this Christmas, but I might get another stab at growing this queen of North American wild foods. And it's really not my fault.
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